diff --git a/common/string_util.cpp b/common/string_util.cpp
index a41f5c184..508304ce1 100644
--- a/common/string_util.cpp
+++ b/common/string_util.cpp
@@ -67,7 +67,7 @@ const std::string str_tolower(std::string s)
 {
 	std::transform(
 		s.begin(), s.end(), s.begin(),
-		[](unsigned char c) { return std::tolower(c); }
+		[](unsigned char c) { return ::tolower(c); }
 	);
 	return s;
 }