diff --git a/idea/src/org/jetbrains/jet/plugin/completion/DescriptorLookupConverter.java b/idea/src/org/jetbrains/jet/plugin/completion/DescriptorLookupConverter.java
index 3cf692c3825..6d86c723ee1 100644
--- a/idea/src/org/jetbrains/jet/plugin/completion/DescriptorLookupConverter.java
+++ b/idea/src/org/jetbrains/jet/plugin/completion/DescriptorLookupConverter.java
@@ -68,6 +68,11 @@ public final class DescriptorLookupConverter {
                 }
             }, ",") + ")";
 
+            boolean extensionFunction = functionDescriptor.getReceiverParameter().exists();
+            DeclarationDescriptor containingDeclaration = descriptor.getContainingDeclaration();
+            if (extensionFunction && containingDeclaration != null) {
+                tailText += " defined in " + DescriptorUtils.getFQName(containingDeclaration);
+            }
 
             // TODO: A special case when it's impossible to resolve type parameters from arguments. Need '<' caret '>'
             // TODO: Support omitting brackets for one argument functions