diff --git a/include/sys/mman.h b/include/sys/mman.h
index 37d36d8..cb1fa21 100644
--- a/include/sys/mman.h
+++ b/include/sys/mman.h
@@ -3,9 +3,9 @@
 #ifndef LIBCRYPTOCOMPAT_MMAN_H
 #define LIBCRYPTOCOMPAT_MMAN_H
 
-#ifndef MAP_ANONYMOUS
-#ifdef MAP_ANON
-#define MAP_ANONYMOUS MAP_ANON
+#ifndef MAP_ANON
+#ifdef MAP_ANONYMOUS
+#define MAP_ANON MAP_ANONYMOUS
 #else
 #error "System does not support mapping anonymous pages?"
 #endif