diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index cc5997d018f..24e04f49caf 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -456,6 +456,8 @@ DIE *DwarfDebug::constructLexicalScopeDIE(CompileUnit *TheCU,
       DebugRangeSymbols.push_back(getLabelBeforeInsn(RI->first));
       DebugRangeSymbols.push_back(getLabelAfterInsn(RI->second));
     }
+
+    // Terminate the range list.
     DebugRangeSymbols.push_back(NULL);
     DebugRangeSymbols.push_back(NULL);
     return ScopeDIE;