diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/ExtendsAutoValue.java b/core/src/main/java/com/google/errorprone/bugpatterns/ExtendsAutoValue.java
index 83c06ab0987..4894cbf376e 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/ExtendsAutoValue.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/ExtendsAutoValue.java
@@ -31,7 +31,7 @@
 @BugPattern(
     name = "ExtendsAutoValue",
     summary = "Do not extend an @AutoValue/@AutoOneOf class in non-generated code.",
-    severity = SeverityLevel.WARNING)
+    severity = SeverityLevel.ERROR)
 public final class ExtendsAutoValue extends BugChecker implements ClassTreeMatcher {
 
   private static final Supplier<ImmutableSet<Name>> AUTOS =
diff --git a/core/src/main/java/com/google/errorprone/scanner/BuiltInCheckerSuppliers.java b/core/src/main/java/com/google/errorprone/scanner/BuiltInCheckerSuppliers.java
index b8a225162ec..d65d08d5f6a 100644
--- a/core/src/main/java/com/google/errorprone/scanner/BuiltInCheckerSuppliers.java
+++ b/core/src/main/java/com/google/errorprone/scanner/BuiltInCheckerSuppliers.java
@@ -518,6 +518,7 @@ public static ScannerSupplier errorChecks() {
           EqualsNaN.class,
           EqualsReference.class,
           EqualsWrongThing.class,
+          ExtendsAutoValue.class,
           ForOverrideChecker.class,
           FormatString.class,
           FormatStringAnnotationChecker.class,
@@ -661,7 +662,6 @@ public static ScannerSupplier errorChecks() {
           EqualsUnsafeCast.class,
           EqualsUsingHashCode.class,
           ExtendingJUnitAssert.class,
-          ExtendsAutoValue.class,
           FallThrough.class,
           Finally.class,
           FloatCast.class,