diff --git a/include/clang/Analysis/ProgramPoint.h b/include/clang/Analysis/ProgramPoint.h
index 0e6a659..71e27c6 100644
--- a/include/clang/Analysis/ProgramPoint.h
+++ b/include/clang/Analysis/ProgramPoint.h
@@ -387,6 +387,7 @@
   virtual StringRef getTagDescription() const = 0;    
 
 protected:
+  /// Used to implement 'classof' in subclasses.
   const void *getTagKind() { return TagKind; }
   
 private: