diff --git a/core/src/main/java/org/teavm/vm/TeaVM.java b/core/src/main/java/org/teavm/vm/TeaVM.java
index 07fcba50c..a4ddb7cda 100644
--- a/core/src/main/java/org/teavm/vm/TeaVM.java
+++ b/core/src/main/java/org/teavm/vm/TeaVM.java
@@ -486,7 +486,9 @@ public class TeaVM implements TeaVMHost, ServiceRepository {
     }
 
     private ListableClassHolderSource lazyPipeline() {
-        return new PostProcessingClassHolderSource();
+        PostProcessingClassHolderSource result = new PostProcessingClassHolderSource();
+        writtenClasses = result;
+        return result;
     }
 
     private void insertClassInit(ListableClassHolderSource classes) {