diff --git a/src/main/java/org/openrewrite/java/dependencies/DependencyVulnerabilityCheck.java b/src/main/java/org/openrewrite/java/dependencies/DependencyVulnerabilityCheck.java
index 0d7c211..37a10a7 100644
--- a/src/main/java/org/openrewrite/java/dependencies/DependencyVulnerabilityCheck.java
+++ b/src/main/java/org/openrewrite/java/dependencies/DependencyVulnerabilityCheck.java
@@ -166,7 +166,7 @@ public Map<ResolvedGroupArtifactVersion, Set<MinimumDepthVulnerability>> upgrade
     public static class Vulnerabilities {
         Map<ResolvedGroupArtifactVersion, Set<MinimumDepthVulnerability>> gavToVulnerabilities;
 
-        public Set<MinimumDepthVulnerability> computeIfAbsent(ResolvedGroupArtifactVersion gav, Function<ResolvedGroupArtifactVersion, Set<MinimumDepthVulnerability>> mappingFunction) {
+        public @Nullable Set<MinimumDepthVulnerability> computeIfAbsent(ResolvedGroupArtifactVersion gav, Function<ResolvedGroupArtifactVersion, Set<MinimumDepthVulnerability>> mappingFunction) {
             return gavToVulnerabilities.computeIfAbsent(gav, mappingFunction);
         }
     }
diff --git a/src/main/java/org/openrewrite/java/dependencies/RemoveExpiredSuppressions.java b/src/main/java/org/openrewrite/java/dependencies/RemoveExpiredSuppressions.java
index 7b81cd0..fd2481e 100644
--- a/src/main/java/org/openrewrite/java/dependencies/RemoveExpiredSuppressions.java
+++ b/src/main/java/org/openrewrite/java/dependencies/RemoveExpiredSuppressions.java
@@ -15,6 +15,7 @@
  */
 package org.openrewrite.java.dependencies;
 
+import org.jspecify.annotations.Nullable;
 import org.openrewrite.ExecutionContext;
 import org.openrewrite.Recipe;
 import org.openrewrite.TreeVisitor;
@@ -41,8 +42,9 @@ public String getDescription() {
     @Override
     public TreeVisitor<?, ExecutionContext> getVisitor() {
         return new XmlIsoVisitor<ExecutionContext>() {
+
             @Override
-            public Xml.Tag visitTag(Xml.Tag tag, ExecutionContext ctx) {
+            public @Nullable Xml.Tag visitTag(Xml.Tag tag, ExecutionContext ctx) {
                 Xml.Tag t = super.visitTag(tag, ctx);
                 if (X_PATH_MATCHER.matches(getCursor())) {
                     Optional<Xml.Attribute> untilAttribute = t.getAttributes().stream()
diff --git a/src/main/java/org/openrewrite/java/dependencies/internal/VersionParser.java b/src/main/java/org/openrewrite/java/dependencies/internal/VersionParser.java
index 2824b42..a78b9ea 100644
--- a/src/main/java/org/openrewrite/java/dependencies/internal/VersionParser.java
+++ b/src/main/java/org/openrewrite/java/dependencies/internal/VersionParser.java
@@ -16,6 +16,8 @@
 
 package org.openrewrite.java.dependencies.internal;
 
+import org.jspecify.annotations.Nullable;
+
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
@@ -27,7 +29,7 @@ public class VersionParser {
     public VersionParser() {
     }
 
-    public Version transform(String original) {
+    public @Nullable Version transform(String original) {
         return cache.computeIfAbsent(original, this::parse);
     }