diff --git a/libc/include/stdint.h b/libc/include/stdint.h
index a889f15..3cd09d4 100644
--- a/libc/include/stdint.h
+++ b/libc/include/stdint.h
@@ -242,7 +242,7 @@
 #  define UINTMAX_MAX	UINT64_MAX
 #endif
 
-#ifndef __STDINT_MACROS
+#ifdef __STDINT_MACROS
 #  define INTMAX_C(c)	INT64_C(c)
 #  define UINTMAX_C(c)	UINT64_C(c)
 #endif