--- a/include/os.h
+++ b/include/os.h
@@ -254,7 +254,7 @@
 typedef int                     int32_t;
 typedef unsigned int            u_int32_t;
 
-# if __GNUC__ >= 2
+# if __GLIBC__ >= 2
 
 #  ifndef int64_t
 typedef long long               int64_t;