diff --git a/src/main/java/org/openrewrite/kotlin/AddImport.java b/src/main/java/org/openrewrite/kotlin/AddImport.java
index 5aee87a82..14feecedf 100644
--- a/src/main/java/org/openrewrite/kotlin/AddImport.java
+++ b/src/main/java/org/openrewrite/kotlin/AddImport.java
@@ -16,9 +16,9 @@
 package org.openrewrite.kotlin;
 
 import lombok.EqualsAndHashCode;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.internal.ListUtils;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.JavaIsoVisitor;
 import org.openrewrite.java.marker.JavaSourceSet;
 import org.openrewrite.java.search.FindMethods;
diff --git a/src/main/java/org/openrewrite/kotlin/Assertions.java b/src/main/java/org/openrewrite/kotlin/Assertions.java
index 8605b1984..9143729dc 100644
--- a/src/main/java/org/openrewrite/kotlin/Assertions.java
+++ b/src/main/java/org/openrewrite/kotlin/Assertions.java
@@ -17,9 +17,9 @@
 
 
 import org.intellij.lang.annotations.Language;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.*;
 import org.openrewrite.internal.ThrowingConsumer;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.search.FindMissingTypes;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.kotlin.marker.Extension;
diff --git a/src/main/java/org/openrewrite/kotlin/FindKotlinSources.java b/src/main/java/org/openrewrite/kotlin/FindKotlinSources.java
index 822cd692e..f40caf24e 100644
--- a/src/main/java/org/openrewrite/kotlin/FindKotlinSources.java
+++ b/src/main/java/org/openrewrite/kotlin/FindKotlinSources.java
@@ -17,8 +17,8 @@
 
 import lombok.EqualsAndHashCode;
 import lombok.Value;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.*;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.kotlin.table.KotlinSourceFile;
 import org.openrewrite.kotlin.tree.K;
 import org.openrewrite.marker.SearchResult;
@@ -65,7 +65,7 @@ public Tree visit(@Nullable Tree tree, ExecutionContext ctx) {
                 return tree;
             }
 
-            private @Nullable KotlinSourceFile.SourceFileType getSourceFileType(SourceFile sourceFile) {
+            private KotlinSourceFile.@Nullable SourceFileType getSourceFileType(SourceFile sourceFile) {
                 KotlinSourceFile.SourceFileType sourceFileType = null;
                 if (sourceFile instanceof K.CompilationUnit) {
                     sourceFileType = KotlinSourceFile.SourceFileType.Kotlin;
diff --git a/src/main/java/org/openrewrite/kotlin/KotlinParser.java b/src/main/java/org/openrewrite/kotlin/KotlinParser.java
index 3ec523875..d1dd87826 100644
--- a/src/main/java/org/openrewrite/kotlin/KotlinParser.java
+++ b/src/main/java/org/openrewrite/kotlin/KotlinParser.java
@@ -63,8 +63,8 @@
 import org.jetbrains.kotlin.psi.KtFile;
 import org.jetbrains.kotlin.resolve.jvm.platform.JvmPlatformAnalyzerServices;
 import org.jetbrains.kotlin.utils.PathUtil;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.*;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.JavaParser;
 import org.openrewrite.java.internal.JavaTypeCache;
 import org.openrewrite.java.marker.JavaSourceSet;
diff --git a/src/main/java/org/openrewrite/kotlin/KotlinVisitor.java b/src/main/java/org/openrewrite/kotlin/KotlinVisitor.java
index 5aea5f98a..8d3871901 100644
--- a/src/main/java/org/openrewrite/kotlin/KotlinVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/KotlinVisitor.java
@@ -15,10 +15,10 @@
  */
 package org.openrewrite.kotlin;
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Cursor;
 import org.openrewrite.SourceFile;
 import org.openrewrite.internal.ListUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.JavaVisitor;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.kotlin.marker.*;
diff --git a/src/main/java/org/openrewrite/kotlin/cleanup/EqualsMethodUsage.java b/src/main/java/org/openrewrite/kotlin/cleanup/EqualsMethodUsage.java
index cb710a3a4..888fc6388 100644
--- a/src/main/java/org/openrewrite/kotlin/cleanup/EqualsMethodUsage.java
+++ b/src/main/java/org/openrewrite/kotlin/cleanup/EqualsMethodUsage.java
@@ -17,8 +17,8 @@
 
 import lombok.EqualsAndHashCode;
 import lombok.Value;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.*;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.tree.Expression;
 import org.openrewrite.java.tree.J;
 import org.openrewrite.java.tree.Space;
@@ -37,8 +37,8 @@
 @Value
 @EqualsAndHashCode(callSuper = false)
 public class EqualsMethodUsage extends Recipe {
-    @Nullable
-    private static J.Binary equalsBinaryTemplate;
+
+    private static J.@Nullable Binary equalsBinaryTemplate;
 
     @Override
     public String getDisplayName() {
diff --git a/src/main/java/org/openrewrite/kotlin/cleanup/RemoveTrailingSemicolon.java b/src/main/java/org/openrewrite/kotlin/cleanup/RemoveTrailingSemicolon.java
index 6a80ff473..9af7efffb 100644
--- a/src/main/java/org/openrewrite/kotlin/cleanup/RemoveTrailingSemicolon.java
+++ b/src/main/java/org/openrewrite/kotlin/cleanup/RemoveTrailingSemicolon.java
@@ -17,11 +17,11 @@
 
 import lombok.EqualsAndHashCode;
 import lombok.Value;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.ExecutionContext;
 import org.openrewrite.PrintOutputCapture;
 import org.openrewrite.Recipe;
 import org.openrewrite.TreeVisitor;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.tree.J;
 import org.openrewrite.java.tree.Space;
 import org.openrewrite.kotlin.KotlinIsoVisitor;
diff --git a/src/main/java/org/openrewrite/kotlin/cleanup/package-info.java b/src/main/java/org/openrewrite/kotlin/cleanup/package-info.java
index 490389621..dbacfd740 100644
--- a/src/main/java/org/openrewrite/kotlin/cleanup/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/cleanup/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin.cleanup;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/main/java/org/openrewrite/kotlin/format/AutoFormatVisitor.java b/src/main/java/org/openrewrite/kotlin/format/AutoFormatVisitor.java
index 946a42df5..fd7807956 100644
--- a/src/main/java/org/openrewrite/kotlin/format/AutoFormatVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/format/AutoFormatVisitor.java
@@ -16,10 +16,10 @@
 package org.openrewrite.kotlin.format;
 
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Cursor;
 import org.openrewrite.SourceFile;
 import org.openrewrite.Tree;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.tree.J;
 import org.openrewrite.java.tree.JavaSourceFile;
 import org.openrewrite.kotlin.KotlinIsoVisitor;
diff --git a/src/main/java/org/openrewrite/kotlin/format/BlankLinesVisitor.java b/src/main/java/org/openrewrite/kotlin/format/BlankLinesVisitor.java
index 24f0aecf3..a8adfd12a 100644
--- a/src/main/java/org/openrewrite/kotlin/format/BlankLinesVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/format/BlankLinesVisitor.java
@@ -16,9 +16,9 @@
 package org.openrewrite.kotlin.format;
 
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Tree;
 import org.openrewrite.internal.ListUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.kotlin.KotlinIsoVisitor;
 import org.openrewrite.kotlin.marker.OmitBraces;
diff --git a/src/main/java/org/openrewrite/kotlin/format/MinimumViableSpacingVisitor.java b/src/main/java/org/openrewrite/kotlin/format/MinimumViableSpacingVisitor.java
index 7831aa484..12cc5b7b1 100644
--- a/src/main/java/org/openrewrite/kotlin/format/MinimumViableSpacingVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/format/MinimumViableSpacingVisitor.java
@@ -16,10 +16,10 @@
 package org.openrewrite.kotlin.format;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Tree;
 import org.openrewrite.internal.ListUtils;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.marker.ImplicitReturn;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.kotlin.KotlinIsoVisitor;
diff --git a/src/main/java/org/openrewrite/kotlin/format/NormalizeFormatVisitor.java b/src/main/java/org/openrewrite/kotlin/format/NormalizeFormatVisitor.java
index 35d171122..f20016911 100644
--- a/src/main/java/org/openrewrite/kotlin/format/NormalizeFormatVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/format/NormalizeFormatVisitor.java
@@ -16,10 +16,10 @@
 package org.openrewrite.kotlin.format;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Tree;
 import org.openrewrite.internal.ListUtils;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.JavaVisitor;
 import org.openrewrite.java.JavadocVisitor;
 import org.openrewrite.java.tree.*;
diff --git a/src/main/java/org/openrewrite/kotlin/format/NormalizeLineBreaksVisitor.java b/src/main/java/org/openrewrite/kotlin/format/NormalizeLineBreaksVisitor.java
index 80ef22443..03e9363aa 100644
--- a/src/main/java/org/openrewrite/kotlin/format/NormalizeLineBreaksVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/format/NormalizeLineBreaksVisitor.java
@@ -15,9 +15,9 @@
  */
 package org.openrewrite.kotlin.format;
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Tree;
 import org.openrewrite.internal.ListUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.JavaVisitor;
 import org.openrewrite.java.JavadocVisitor;
 import org.openrewrite.java.tree.*;
diff --git a/src/main/java/org/openrewrite/kotlin/format/NormalizeTabsOrSpacesVisitor.java b/src/main/java/org/openrewrite/kotlin/format/NormalizeTabsOrSpacesVisitor.java
index 7860db364..545591ad6 100644
--- a/src/main/java/org/openrewrite/kotlin/format/NormalizeTabsOrSpacesVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/format/NormalizeTabsOrSpacesVisitor.java
@@ -16,11 +16,11 @@
 package org.openrewrite.kotlin.format;
 
 
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Tree;
 import org.openrewrite.internal.ListUtils;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.NonNull;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.JavaVisitor;
 import org.openrewrite.java.JavadocVisitor;
 import org.openrewrite.java.tree.*;
diff --git a/src/main/java/org/openrewrite/kotlin/format/RemoveTrailingWhitespaceVisitor.java b/src/main/java/org/openrewrite/kotlin/format/RemoveTrailingWhitespaceVisitor.java
index 615068e27..56c506129 100644
--- a/src/main/java/org/openrewrite/kotlin/format/RemoveTrailingWhitespaceVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/format/RemoveTrailingWhitespaceVisitor.java
@@ -17,8 +17,8 @@
 
 
 import com.fasterxml.jackson.annotation.JsonCreator;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Tree;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.tree.J;
 import org.openrewrite.java.tree.JavaSourceFile;
 import org.openrewrite.java.tree.Space;
diff --git a/src/main/java/org/openrewrite/kotlin/format/SpacesFromCompilationUnitStyle.java b/src/main/java/org/openrewrite/kotlin/format/SpacesFromCompilationUnitStyle.java
index e9f8c2383..48be5b636 100644
--- a/src/main/java/org/openrewrite/kotlin/format/SpacesFromCompilationUnitStyle.java
+++ b/src/main/java/org/openrewrite/kotlin/format/SpacesFromCompilationUnitStyle.java
@@ -15,9 +15,9 @@
  */
 package org.openrewrite.kotlin.format;
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.ExecutionContext;
 import org.openrewrite.Tree;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.tree.J;
 import org.openrewrite.kotlin.KotlinIsoVisitor;
 import org.openrewrite.kotlin.style.IntelliJ;
diff --git a/src/main/java/org/openrewrite/kotlin/format/SpacesVisitor.java b/src/main/java/org/openrewrite/kotlin/format/SpacesVisitor.java
index 5babb3660..46ea4d727 100644
--- a/src/main/java/org/openrewrite/kotlin/format/SpacesVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/format/SpacesVisitor.java
@@ -15,11 +15,11 @@
  */
 package org.openrewrite.kotlin.format;
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.PrintOutputCapture;
 import org.openrewrite.Tree;
 import org.openrewrite.internal.ListUtils;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.marker.OmitParentheses;
 import org.openrewrite.java.marker.TrailingComma;
 import org.openrewrite.java.tree.*;
diff --git a/src/main/java/org/openrewrite/kotlin/format/TabsAndIndentsVisitor.java b/src/main/java/org/openrewrite/kotlin/format/TabsAndIndentsVisitor.java
index f26416411..83714839e 100644
--- a/src/main/java/org/openrewrite/kotlin/format/TabsAndIndentsVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/format/TabsAndIndentsVisitor.java
@@ -15,11 +15,11 @@
  */
 package org.openrewrite.kotlin.format;
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Cursor;
 import org.openrewrite.Tree;
 import org.openrewrite.internal.ListUtils;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.marker.ImplicitReturn;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.kotlin.KotlinIsoVisitor;
diff --git a/src/main/java/org/openrewrite/kotlin/format/WrappingAndBracesVisitor.java b/src/main/java/org/openrewrite/kotlin/format/WrappingAndBracesVisitor.java
index c0e57e906..7195d2962 100644
--- a/src/main/java/org/openrewrite/kotlin/format/WrappingAndBracesVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/format/WrappingAndBracesVisitor.java
@@ -16,10 +16,10 @@
 package org.openrewrite.kotlin.format;
 
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Cursor;
 import org.openrewrite.Tree;
 import org.openrewrite.internal.ListUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.kotlin.KotlinIsoVisitor;
 import org.openrewrite.kotlin.marker.OmitBraces;
diff --git a/src/main/java/org/openrewrite/kotlin/format/package-info.java b/src/main/java/org/openrewrite/kotlin/format/package-info.java
index 9bff646e4..164c9bfb8 100644
--- a/src/main/java/org/openrewrite/kotlin/format/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/format/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin.format;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/main/java/org/openrewrite/kotlin/internal/KotlinPrinter.java b/src/main/java/org/openrewrite/kotlin/internal/KotlinPrinter.java
index 96e32599b..6820fb838 100755
--- a/src/main/java/org/openrewrite/kotlin/internal/KotlinPrinter.java
+++ b/src/main/java/org/openrewrite/kotlin/internal/KotlinPrinter.java
@@ -15,10 +15,10 @@
  */
 package org.openrewrite.kotlin.internal;
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Cursor;
 import org.openrewrite.PrintOutputCapture;
 import org.openrewrite.Tree;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.JavaPrinter;
 import org.openrewrite.java.marker.ImplicitReturn;
 import org.openrewrite.java.marker.OmitParentheses;
@@ -645,7 +645,7 @@ public J visitClassDeclaration(J.ClassDeclaration classDecl, PrintOutputCapture<
             return visitClassDeclaration0(classDecl, null, p);
         }
 
-        private J.ClassDeclaration visitClassDeclaration0(J.ClassDeclaration classDecl, @Nullable K.TypeConstraints typeConstraints, PrintOutputCapture<P> p) {
+        private J.ClassDeclaration visitClassDeclaration0(J.ClassDeclaration classDecl, K.@Nullable TypeConstraints typeConstraints, PrintOutputCapture<P> p) {
             beforeSyntax(classDecl, Space.Location.CLASS_DECLARATION_PREFIX, p);
             visit(classDecl.getLeadingAnnotations(), p);
             for (J.Modifier m : classDecl.getModifiers()) {
@@ -884,7 +884,7 @@ public J visitMethodDeclaration(J.MethodDeclaration method, PrintOutputCapture<P
             return visitMethodDeclaration0(method, null, p);
         }
 
-        private J.MethodDeclaration visitMethodDeclaration0(J.MethodDeclaration method, @Nullable K.TypeConstraints typeConstraints, PrintOutputCapture<P> p) {
+        private J.MethodDeclaration visitMethodDeclaration0(J.MethodDeclaration method, K.@Nullable TypeConstraints typeConstraints, PrintOutputCapture<P> p) {
             // Do not print generated methods.
             for (Marker marker : method.getMarkers().getMarkers()) {
                 if (marker instanceof Implicit || marker instanceof PrimaryConstructor) {
@@ -1404,7 +1404,7 @@ private void beforeSyntax(J j, Space.Location loc, PrintOutputCapture<P> p) {
         beforeSyntax(j.getPrefix(), j.getMarkers(), loc, p);
     }
 
-    private void beforeSyntax(Space prefix, Markers markers, @Nullable KSpace.Location loc, PrintOutputCapture<P> p) {
+    private void beforeSyntax(Space prefix, Markers markers, KSpace.@Nullable Location loc, PrintOutputCapture<P> p) {
         for (Marker marker : markers.getMarkers()) {
             p.append(p.getMarkerPrinter().beforePrefix(marker, new Cursor(getCursor(), marker), JAVA_MARKER_WRAPPER));
         }
@@ -1421,7 +1421,7 @@ private void beforeSyntax(K k, Space.Location loc, PrintOutputCapture<P> p) {
         beforeSyntax(k.getPrefix(), k.getMarkers(), loc, p);
     }
 
-    private void beforeSyntax(Space prefix, Markers markers, @Nullable Space.Location loc, PrintOutputCapture<P> p) {
+    private void beforeSyntax(Space prefix, Markers markers, Space.@Nullable Location loc, PrintOutputCapture<P> p) {
         for (Marker marker : markers.getMarkers()) {
             p.append(p.getMarkerPrinter().beforePrefix(marker, new Cursor(getCursor(), marker), JAVA_MARKER_WRAPPER));
         }
diff --git a/src/main/java/org/openrewrite/kotlin/internal/KotlinTreeParserVisitor.java b/src/main/java/org/openrewrite/kotlin/internal/KotlinTreeParserVisitor.java
index 8e7f374fe..0e6a11f98 100644
--- a/src/main/java/org/openrewrite/kotlin/internal/KotlinTreeParserVisitor.java
+++ b/src/main/java/org/openrewrite/kotlin/internal/KotlinTreeParserVisitor.java
@@ -38,14 +38,14 @@
 import org.jetbrains.kotlin.parsing.ParseUtilsKt;
 import org.jetbrains.kotlin.psi.*;
 import org.jetbrains.kotlin.psi.psiUtil.PsiUtilsKt;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.ExecutionContext;
 import org.openrewrite.FileAttributes;
 import org.openrewrite.ParseExceptionResult;
 import org.openrewrite.Tree;
 import org.openrewrite.internal.EncodingDetectingInputStream;
 import org.openrewrite.internal.ListUtils;
-import org.openrewrite.internal.lang.NonNull;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.marker.ImplicitReturn;
 import org.openrewrite.java.marker.OmitParentheses;
 import org.openrewrite.java.marker.Quoted;
@@ -1923,7 +1923,7 @@ public J visitBinaryExpression(KtBinaryExpression expression, ExecutionContext d
         return mapFunctionCall(expression, data);
     }
 
-    private @Nullable J.AssignmentOperation.Type mapAssignmentOperationType(KtOperationReferenceExpression operationReference) {
+    private J.AssignmentOperation.@Nullable Type mapAssignmentOperationType(KtOperationReferenceExpression operationReference) {
         IElementType elementType = operationReference.getOperationSignTokenType();
 
         if (elementType == KtTokens.PLUSEQ) {
@@ -3301,7 +3301,7 @@ public J visitValueArgumentList(KtValueArgumentList list, ExecutionContext data)
     /*====================================================================
      * Mapping methods
      * ====================================================================*/
-    private @Nullable K.Binary.Type mapKBinaryType(KtOperationReferenceExpression operationReference) {
+    private K.Binary.@Nullable Type mapKBinaryType(KtOperationReferenceExpression operationReference) {
         IElementType elementType = operationReference.getOperationSignTokenType();
         if (elementType == null) {
             return null;
@@ -3328,7 +3328,7 @@ public J visitValueArgumentList(KtValueArgumentList list, ExecutionContext data)
         }
     }
 
-    private @Nullable J.Binary.Type mapJBinaryType(KtOperationReferenceExpression operationReference) {
+    private J.Binary.@Nullable Type mapJBinaryType(KtOperationReferenceExpression operationReference) {
         IElementType elementType = operationReference.getOperationSignTokenType();
 
         if (elementType == null) {
@@ -3378,7 +3378,7 @@ else if (elementType == KtTokens.OROR)
             return null;
     }
 
-    private @Nullable J.Unary.Type mapJUnaryType(KtSimpleNameExpression operationReference) {
+    private J.Unary.@Nullable Type mapJUnaryType(KtSimpleNameExpression operationReference) {
         IElementType elementType = operationReference.getReferencedNameElementType();
 
         if (elementType == KtTokens.EXCL) {
@@ -3444,7 +3444,7 @@ private JRightPadded<Statement> buildIfThenPart(KtIfExpression expression) {
                 Space.EMPTY);
     }
 
-    private @Nullable J.If.Else buildIfElsePart(KtIfExpression expression) {
+    private J.If.@Nullable Else buildIfElsePart(KtIfExpression expression) {
         if (expression.getElse() == null) {
             return null;
         }
@@ -3637,15 +3637,15 @@ private JavaType.Primitive primitiveType(PsiElement psi) {
         return psiElementAssociations.primitiveType(psi);
     }
 
-    private @Nullable JavaType.Variable variableType(PsiElement psi, @Nullable FirElement parent) {
+    private JavaType.@Nullable Variable variableType(PsiElement psi, @Nullable FirElement parent) {
         return psiElementAssociations.variableType(psi, parent);
     }
 
-    private @Nullable JavaType.Method methodDeclarationType(PsiElement psi) {
+    private JavaType.@Nullable Method methodDeclarationType(PsiElement psi) {
         return psiElementAssociations.methodDeclarationType(psi);
     }
 
-    private @Nullable JavaType.Method methodInvocationType(PsiElement psi) {
+    private JavaType.@Nullable Method methodInvocationType(PsiElement psi) {
         return psiElementAssociations.methodInvocationType(psi);
     }
 
@@ -3669,7 +3669,7 @@ private J.Identifier createIdentifier(String name, Space prefix,
 
     private J.Identifier createIdentifier(String name, Space prefix,
                                           @Nullable JavaType type,
-                                          @Nullable JavaType.Variable fieldType) {
+            JavaType.@Nullable Variable fieldType) {
         Markers markers = Markers.EMPTY;
         String updated = name;
         if (name.startsWith("`")) {
diff --git a/src/main/java/org/openrewrite/kotlin/internal/PsiTreePrinter.java b/src/main/java/org/openrewrite/kotlin/internal/PsiTreePrinter.java
index d37e0b1b8..49846088d 100644
--- a/src/main/java/org/openrewrite/kotlin/internal/PsiTreePrinter.java
+++ b/src/main/java/org/openrewrite/kotlin/internal/PsiTreePrinter.java
@@ -40,8 +40,8 @@
 import org.jetbrains.kotlin.name.ClassId;
 import org.jetbrains.kotlin.name.FqName;
 import org.jetbrains.kotlin.psi.psiUtil.PsiUtilsKt;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.*;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.internal.JavaTypeCache;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.kotlin.KotlinIrTypeMapping;
diff --git a/src/main/java/org/openrewrite/kotlin/internal/package-info.java b/src/main/java/org/openrewrite/kotlin/internal/package-info.java
index de64c72ae..baaaa84ed 100644
--- a/src/main/java/org/openrewrite/kotlin/internal/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/internal/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin.internal;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/main/java/org/openrewrite/kotlin/internal/template/package-info.java b/src/main/java/org/openrewrite/kotlin/internal/template/package-info.java
index aad0d0987..d27983de1 100644
--- a/src/main/java/org/openrewrite/kotlin/internal/template/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/internal/template/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin.internal.template;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/main/java/org/openrewrite/kotlin/marker/IsNullSafe.java b/src/main/java/org/openrewrite/kotlin/marker/IsNullSafe.java
index 19873a8db..d53288923 100644
--- a/src/main/java/org/openrewrite/kotlin/marker/IsNullSafe.java
+++ b/src/main/java/org/openrewrite/kotlin/marker/IsNullSafe.java
@@ -19,7 +19,7 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import lombok.Value;
 import lombok.With;
-import org.openrewrite.internal.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.java.tree.Space;
 import org.openrewrite.marker.Marker;
 
diff --git a/src/main/java/org/openrewrite/kotlin/marker/KObject.java b/src/main/java/org/openrewrite/kotlin/marker/KObject.java
index 1e71a8b09..581914d91 100644
--- a/src/main/java/org/openrewrite/kotlin/marker/KObject.java
+++ b/src/main/java/org/openrewrite/kotlin/marker/KObject.java
@@ -19,7 +19,7 @@
 import com.fasterxml.jackson.annotation.JsonProperty;
 import lombok.Value;
 import lombok.With;
-import org.openrewrite.internal.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.java.tree.Space;
 import org.openrewrite.marker.Marker;
 
diff --git a/src/main/java/org/openrewrite/kotlin/marker/package-info.java b/src/main/java/org/openrewrite/kotlin/marker/package-info.java
index 4dd782244..d80f9727c 100644
--- a/src/main/java/org/openrewrite/kotlin/marker/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/marker/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin.marker;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/main/java/org/openrewrite/kotlin/package-info.java b/src/main/java/org/openrewrite/kotlin/package-info.java
index 338fe11cb..1902d78fd 100644
--- a/src/main/java/org/openrewrite/kotlin/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/main/java/org/openrewrite/kotlin/search/package-info.java b/src/main/java/org/openrewrite/kotlin/search/package-info.java
index d1c0102b9..d9694e198 100644
--- a/src/main/java/org/openrewrite/kotlin/search/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/search/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin.search;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/main/java/org/openrewrite/kotlin/service/KotlinAutoFormatService.java b/src/main/java/org/openrewrite/kotlin/service/KotlinAutoFormatService.java
index 5e2f7accc..2d2d7dc82 100644
--- a/src/main/java/org/openrewrite/kotlin/service/KotlinAutoFormatService.java
+++ b/src/main/java/org/openrewrite/kotlin/service/KotlinAutoFormatService.java
@@ -15,8 +15,8 @@
  */
 package org.openrewrite.kotlin.service;
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.Tree;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.JavaVisitor;
 import org.openrewrite.java.service.AutoFormatService;
 import org.openrewrite.kotlin.format.AutoFormatVisitor;
diff --git a/src/main/java/org/openrewrite/kotlin/service/KotlinImportService.java b/src/main/java/org/openrewrite/kotlin/service/KotlinImportService.java
index b4e146943..728fc6a9a 100644
--- a/src/main/java/org/openrewrite/kotlin/service/KotlinImportService.java
+++ b/src/main/java/org/openrewrite/kotlin/service/KotlinImportService.java
@@ -15,7 +15,7 @@
  */
 package org.openrewrite.kotlin.service;
 
-import org.openrewrite.internal.lang.Nullable;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.java.JavaVisitor;
 import org.openrewrite.java.service.ImportService;
 import org.openrewrite.kotlin.AddImport;
diff --git a/src/main/java/org/openrewrite/kotlin/service/package-info.java b/src/main/java/org/openrewrite/kotlin/service/package-info.java
index 5a02e4b7a..aed168883 100644
--- a/src/main/java/org/openrewrite/kotlin/service/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/service/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin.service;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/main/java/org/openrewrite/kotlin/style/Autodetect.java b/src/main/java/org/openrewrite/kotlin/style/Autodetect.java
index c87473805..54d3b9742 100644
--- a/src/main/java/org/openrewrite/kotlin/style/Autodetect.java
+++ b/src/main/java/org/openrewrite/kotlin/style/Autodetect.java
@@ -19,11 +19,11 @@
 import lombok.Data;
 import lombok.EqualsAndHashCode;
 import lombok.Value;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.SourceFile;
 import org.openrewrite.Tree;
 import org.openrewrite.internal.ListUtils;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.marker.TrailingComma;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.kotlin.KotlinIsoVisitor;
diff --git a/src/main/java/org/openrewrite/kotlin/style/ImportLayoutStyle.java b/src/main/java/org/openrewrite/kotlin/style/ImportLayoutStyle.java
index 62eb87f04..eab92d63a 100644
--- a/src/main/java/org/openrewrite/kotlin/style/ImportLayoutStyle.java
+++ b/src/main/java/org/openrewrite/kotlin/style/ImportLayoutStyle.java
@@ -28,9 +28,9 @@
 import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
 import lombok.EqualsAndHashCode;
 import lombok.Getter;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.internal.ListUtils;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.tree.*;
 import org.openrewrite.kotlin.KotlinStyle;
 import org.openrewrite.kotlin.internal.KotlinPrinter;
@@ -115,7 +115,7 @@ public ImportLayoutStyle(int topLevelSymbolsToUseStarImport,
      * @return The import list with a new import added.
      */
     public List<JRightPadded<J.Import>> addImport(List<JRightPadded<J.Import>> originalImports,
-                                                  J.Import toAdd, @Nullable J.Package pkg,
+                                                  J.Import toAdd, J.@Nullable Package pkg,
                                                   Collection<JavaType.FullyQualified> classpath) {
         JRightPadded<J.Import> paddedToAdd = new JRightPadded<>(toAdd, Space.EMPTY, Markers.EMPTY);
 
diff --git a/src/main/java/org/openrewrite/kotlin/style/package-info.java b/src/main/java/org/openrewrite/kotlin/style/package-info.java
index 692ca5027..01b7f8e70 100644
--- a/src/main/java/org/openrewrite/kotlin/style/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/style/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin.style;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/main/java/org/openrewrite/kotlin/table/package-info.java b/src/main/java/org/openrewrite/kotlin/table/package-info.java
index 92d0a4d9f..134630469 100644
--- a/src/main/java/org/openrewrite/kotlin/table/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/table/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin.table;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/main/java/org/openrewrite/kotlin/tree/K.java b/src/main/java/org/openrewrite/kotlin/tree/K.java
index cb98c05dc..096cd88dd 100644
--- a/src/main/java/org/openrewrite/kotlin/tree/K.java
+++ b/src/main/java/org/openrewrite/kotlin/tree/K.java
@@ -20,9 +20,9 @@
 import lombok.*;
 import lombok.experimental.FieldDefaults;
 import lombok.experimental.NonFinal;
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.*;
 import org.openrewrite.internal.ListUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.JavaPrinter;
 import org.openrewrite.java.JavaTypeVisitor;
 import org.openrewrite.java.internal.TypesInUse;
@@ -1552,9 +1552,9 @@ public Property(UUID id,
                         JContainer<TypeParameter> typeParameters,
                         @Nullable JRightPadded<J.VariableDeclarations> paddedVariableDeclarations,
                         @Nullable VariableDeclarations variableDeclarations,
-                        @Nullable K.TypeConstraints typeConstraints,
-                        @Nullable @JsonProperty("getter") J.MethodDeclaration getter,
-                        @Nullable @JsonProperty("setter") J.MethodDeclaration setter,
+                K.@Nullable TypeConstraints typeConstraints,
+                @JsonProperty("getter") J.@Nullable MethodDeclaration getter,
+                @JsonProperty("setter") J.@Nullable MethodDeclaration setter,
                         @Nullable @JsonProperty("isSetterFirst") Boolean isSetterFirst,
                         JContainer<J.MethodDeclaration> accessors,
                         @Nullable JRightPadded<Expression> receiver
@@ -1687,10 +1687,9 @@ final class Return implements K, Statement, Expression {
 
         J.Return expression;
 
-        @Nullable
-        J.Identifier label;
+        J.@Nullable Identifier label;
 
-        public Return(UUID id, J.Return expression, @Nullable J.Identifier label) {
+        public Return(UUID id, J.Return expression, J.@Nullable Identifier label) {
             this(id, Collections.emptyList(), expression, label);
         }
 
@@ -1923,8 +1922,7 @@ final class This implements K, Expression {
         Space prefix;
         Markers markers;
 
-        @Nullable
-        J.Identifier label;
+        J.@Nullable Identifier label;
 
         @Nullable
         JavaType type;
diff --git a/src/main/java/org/openrewrite/kotlin/tree/package-info.java b/src/main/java/org/openrewrite/kotlin/tree/package-info.java
index 0534c44b5..43b2eaf38 100644
--- a/src/main/java/org/openrewrite/kotlin/tree/package-info.java
+++ b/src/main/java/org/openrewrite/kotlin/tree/package-info.java
@@ -13,9 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-@NonNullApi
+@NullMarked
 @NonNullFields
 package org.openrewrite.kotlin.tree;
 
-import org.openrewrite.internal.lang.NonNullApi;
+import org.jspecify.annotations.NullMarked;
 import org.openrewrite.internal.lang.NonNullFields;
diff --git a/src/test/java/org/openrewrite/kotlin/KotlinIrTypeMappingTest.java b/src/test/java/org/openrewrite/kotlin/KotlinIrTypeMappingTest.java
index fe37ef27c..79291c67c 100644
--- a/src/test/java/org/openrewrite/kotlin/KotlinIrTypeMappingTest.java
+++ b/src/test/java/org/openrewrite/kotlin/KotlinIrTypeMappingTest.java
@@ -18,6 +18,7 @@
 import org.jetbrains.kotlin.com.intellij.openapi.Disposable;
 import org.jetbrains.kotlin.com.intellij.openapi.util.Disposer;
 import org.jetbrains.kotlin.ir.declarations.*;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Nested;
@@ -25,7 +26,6 @@
 import org.openrewrite.InMemoryExecutionContext;
 import org.openrewrite.Parser;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.java.internal.JavaTypeCache;
 import org.openrewrite.kotlin.internal.CompiledSource;
 import org.openrewrite.test.RewriteTest;
diff --git a/src/test/java/org/openrewrite/kotlin/KotlinTypeIrSignatureBuilderTest.java b/src/test/java/org/openrewrite/kotlin/KotlinTypeIrSignatureBuilderTest.java
index ff834f1d3..b5a4c18ed 100644
--- a/src/test/java/org/openrewrite/kotlin/KotlinTypeIrSignatureBuilderTest.java
+++ b/src/test/java/org/openrewrite/kotlin/KotlinTypeIrSignatureBuilderTest.java
@@ -18,13 +18,13 @@
 import org.jetbrains.kotlin.com.intellij.openapi.Disposable;
 import org.jetbrains.kotlin.com.intellij.openapi.util.Disposer;
 import org.jetbrains.kotlin.ir.declarations.*;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.openrewrite.InMemoryExecutionContext;
 import org.openrewrite.Parser;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.kotlin.internal.CompiledSource;
 import org.openrewrite.tree.ParsingExecutionContextView;
 
diff --git a/src/test/java/org/openrewrite/kotlin/KotlinTypeSignatureBuilderTest.java b/src/test/java/org/openrewrite/kotlin/KotlinTypeSignatureBuilderTest.java
index 4dc1ad7dc..cbf5a2c4f 100644
--- a/src/test/java/org/openrewrite/kotlin/KotlinTypeSignatureBuilderTest.java
+++ b/src/test/java/org/openrewrite/kotlin/KotlinTypeSignatureBuilderTest.java
@@ -18,13 +18,13 @@
 import org.jetbrains.kotlin.com.intellij.openapi.Disposable;
 import org.jetbrains.kotlin.com.intellij.openapi.util.Disposer;
 import org.jetbrains.kotlin.fir.declarations.*;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterAll;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.openrewrite.InMemoryExecutionContext;
 import org.openrewrite.Parser;
 import org.openrewrite.internal.StringUtils;
-import org.openrewrite.internal.lang.Nullable;
 import org.openrewrite.kotlin.internal.CompiledSource;
 import org.openrewrite.tree.ParsingExecutionContextView;