diff --git a/src/lib-mem.c b/src/lib-mem.c
index cadb5c1..eb509c4 100644
--- a/src/lib-mem.c
+++ b/src/lib-mem.c
@@ -60,6 +60,10 @@
 #   define SIGKILL 9
 #endif
 
+#if !defined MAP_ANONYMOUS
+#   define MAP_ANONYMOUS MAP_ANON
+#endif
+
 /* TODO: mremap, maybe brk/sbrk (haha) */
 
 /* Library functions that we divert */