diff --git a/lib/Transforms/Utils/LowerSwitch.cpp b/lib/Transforms/Utils/LowerSwitch.cpp
index 17e40e1a23a..5c20a81a5af 100644
--- a/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/lib/Transforms/Utils/LowerSwitch.cpp
@@ -109,6 +109,8 @@ bool LowerSwitch::runOnFunction(Function &F) {
 
 // operator<< - Used for debugging purposes.
 //
+static raw_ostream& operator<<(raw_ostream &O,
+                               const LowerSwitch::CaseVector &C) __attribute((used));
 static raw_ostream& operator<<(raw_ostream &O,
                                const LowerSwitch::CaseVector &C) {
   O << "[";