diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java
index c5415ab5758..d35ec4ad10b 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/ImplementationBodyCodegen.java
@@ -365,6 +365,8 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
         if (context.closure != null)
             genClosureFields(context.closure, v, typeMapper);
 
+        if (state.getClassBuilderMode() == ClassBuilderMode.LIGHT_CLASSES) return;
+
         for (ExpressionCodegenExtension extension : ExpressionCodegenExtension.Companion.getInstances(state.getProject())) {
             extension.generateClassSyntheticParts(this);
         }