diff --git a/Core/HLE/sceHttp.cpp b/Core/HLE/sceHttp.cpp
index d5174aae044d..9219b87e7dfc 100644
--- a/Core/HLE/sceHttp.cpp
+++ b/Core/HLE/sceHttp.cpp
@@ -56,7 +56,7 @@ int HTTPTemplate::addRequestHeader(const char* name, const char* value, u32 mode
 	// Handle User-Agent separately, since PSP Browser seems to add "User-Agent" header manually
 	if (mode == SCE_HTTP_HEADER_OVERWRITE) {
 		std::string s = name;
-		std::transform(s.begin(), s.end(), s.begin(), std::tolower);
+		std::transform(s.begin(), s.end(), s.begin(), static_cast<int(*)(int)>(std::tolower));
 		if (s == "user-agent")
 			setUserAgent(value);
 	}