diff --git a/Internal.h b/Internal.h
index c3555c3..c9d5833 100644
--- a/Internal.h
+++ b/Internal.h
@@ -538,7 +538,7 @@ struct ReferenceImpl {
 
 using Key = ConflictSet::Key;
 
-inline Key operator"" _s(const char *str, size_t size) {
+inline Key operator""_s(const char *str, size_t size) {
   return {reinterpret_cast<const uint8_t *>(str), int(size)};
 }