diff --git a/httplib.h b/httplib.h
index 11faac889f..aef0c1ec79 100644
--- a/httplib.h
+++ b/httplib.h
@@ -3759,7 +3759,7 @@ inline unsigned int str2tag(const std::string &s) {
 
 namespace udl {
 
-inline constexpr unsigned int operator"" _t(const char *s, size_t l) {
+inline constexpr unsigned int operator""_t(const char *s, size_t l) {
   return str2tag_core(s, l, 0);
 }