diff --git a/platform/core-api/src/com/intellij/lang/PsiBuilder.java b/platform/core-api/src/com/intellij/lang/PsiBuilder.java
index 2000064136be..0b234c084161 100644
--- a/platform/core-api/src/com/intellij/lang/PsiBuilder.java
+++ b/platform/core-api/src/com/intellij/lang/PsiBuilder.java
@@ -76,10 +76,8 @@ public interface PsiBuilder extends UserDataHolder, UserDataHolderUnprotected {
   /**
    * Subscribe for notification on default whitespace and comments skipped events.
    * @param callback an implementation for the callback
-   * @return previously registered callback
    */
-  @Nullable
-  WhitespaceSkippedCallback setWhitespaceSkippedCallback(@Nullable WhitespaceSkippedCallback callback);
+  void setWhitespaceSkippedCallback(@Nullable WhitespaceSkippedCallback callback);
 
   /**
    * See what token type is in <code>steps</code> ahead
diff --git a/platform/core-impl/src/com/intellij/lang/impl/PsiBuilderAdapter.java b/platform/core-impl/src/com/intellij/lang/impl/PsiBuilderAdapter.java
index 6f7b36a3bdfa..051da297750a 100644
--- a/platform/core-impl/src/com/intellij/lang/impl/PsiBuilderAdapter.java
+++ b/platform/core-impl/src/com/intellij/lang/impl/PsiBuilderAdapter.java
@@ -62,9 +62,8 @@ public class PsiBuilderAdapter implements PsiBuilder {
   }
 
   @Override
-  @Nullable
-  public WhitespaceSkippedCallback setWhitespaceSkippedCallback(@Nullable final WhitespaceSkippedCallback callback) {
-    return myDelegate.setWhitespaceSkippedCallback(callback);
+  public void setWhitespaceSkippedCallback(@Nullable final WhitespaceSkippedCallback callback) {
+    myDelegate.setWhitespaceSkippedCallback(callback);
   }
 
   @Override
diff --git a/platform/core-impl/src/com/intellij/lang/impl/PsiBuilderImpl.java b/platform/core-impl/src/com/intellij/lang/impl/PsiBuilderImpl.java
index 53c7ed371520..4dfb8a1cb2bd 100644
--- a/platform/core-impl/src/com/intellij/lang/impl/PsiBuilderImpl.java
+++ b/platform/core-impl/src/com/intellij/lang/impl/PsiBuilderImpl.java
@@ -734,11 +734,8 @@ public class PsiBuilderImpl extends UserDataHolderBase implements PsiBuilder {
   }
 
   @Override
-  @Nullable
-  public WhitespaceSkippedCallback setWhitespaceSkippedCallback(@Nullable final WhitespaceSkippedCallback callback) {
-    final WhitespaceSkippedCallback oldCallback = myWhitespaceSkippedCallback;
+  public void setWhitespaceSkippedCallback(@Nullable final WhitespaceSkippedCallback callback) {
     myWhitespaceSkippedCallback = callback;
-    return oldCallback;
   }
 
   @Override