diff --git a/src/load.c b/src/load.c
index 7acd3e7..d88a704 100644
--- a/src/load.c
+++ b/src/load.c
@@ -447,7 +447,7 @@ out:
 }
 
 #if JSON_INTEGER_IS_LONG_LONG
-#ifdef _WIN32
+#ifdef _MSC_VER // Microsoft Visual Studio
 #define json_strtoint     _strtoi64
 #else
 #define json_strtoint     strtoll