diff --git a/include/llvm/Support/StringExtras.h b/include/llvm/Support/StringExtras.h
index 22d02c3140a..569ae4240b9 100644
--- a/include/llvm/Support/StringExtras.h
+++ b/include/llvm/Support/StringExtras.h
@@ -64,7 +64,7 @@ static inline string itostr(int X) {
 
 static inline string ftostr(double V) {
   char Buffer[200];
-  snprintf(Buffer, 200, "%f", V);
+  snprintf(Buffer, 200, "%e", V);
   return Buffer;
 }