diff --git a/lib/CodeGen/LiveDebugVariables.cpp b/lib/CodeGen/LiveDebugVariables.cpp
index 2187833..5b7941f 100644
--- a/lib/CodeGen/LiveDebugVariables.cpp
+++ b/lib/CodeGen/LiveDebugVariables.cpp
@@ -721,7 +721,8 @@
 
   if (TargetRegisterInfo::isVirtualRegister(NewReg))
     mapVirtReg(NewReg, UV);
-  virtRegToEqClass.erase(OldReg);
+  if (OldReg != NewReg)
+    virtRegToEqClass.erase(OldReg);
 
   do {
     UV->renameRegister(OldReg, NewReg, SubIdx, TRI);