diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 1b1b4fe..1796626 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -494,7 +494,8 @@
     ParamInfo = new (Mem) ParmVarDecl*[NumParams];
     memcpy(ParamInfo, NewParamInfo, sizeof(ParmVarDecl*)*NumParams);
 
-    // Update source range.
+    // Update source range. The check below allows us to set EndRangeLoc before
+    // setting the parameters.
     if (EndRangeLoc < NewParamInfo[NumParams-1]->getLocEnd())
       EndRangeLoc = NewParamInfo[NumParams-1]->getLocEnd();
   }