diff --git a/xpcom/ds/nsCRT.cpp b/xpcom/ds/nsCRT.cpp
index 4c6c3d0db45a..5f3c043d4f22 100644
--- a/xpcom/ds/nsCRT.cpp
+++ b/xpcom/ds/nsCRT.cpp
@@ -129,7 +129,9 @@ static NS_DEFINE_CID(kUnicharUtilCID, NS_UNICHARUTIL_CID);
 
 extern nsICaseConversion * gCaseConv;
 
+#ifdef STANDALONE_STRING_TESTS
 static nsICaseConversion* gCaseConv;
+#endif
 
 static void CheckCaseConversion()
 {