diff --git a/lib/CodeGen/MachineFunction.cpp b/lib/CodeGen/MachineFunction.cpp
index fc9aa843e78..38dd4033fb9 100644
--- a/lib/CodeGen/MachineFunction.cpp
+++ b/lib/CodeGen/MachineFunction.cpp
@@ -398,7 +398,7 @@ unsigned MachineFunction::getOrCreateDebugLocID(unsigned Src, unsigned Line,
 
 /// getDebugLocTuple - Get the DebugLocTuple for a given DebugLoc object.
 const DebugLocTuple &MachineFunction::getDebugLocTuple(DebugLoc DL) {
-  unsigned Idx;
+  unsigned Idx = DL.getIndex();
   assert(Idx < DebugLocInfo.DebugLocations.size() &&
          "Invalid index into debug locations!");
   return DebugLocInfo.DebugLocations[Idx];