diff --git a/crypto/mem_sec.c b/crypto/mem_sec.c
index e28a43e295..ddc0a370e6 100644
--- a/crypto/mem_sec.c
+++ b/crypto/mem_sec.c
@@ -514,7 +514,7 @@ static void sh_done(void)
     OPENSSL_free(sh.freelist);
     OPENSSL_free(sh.bittable);
     OPENSSL_free(sh.bitmalloc);
-    if (sh.map_result != NULL && sh.map_size)
+    if (sh.map_result != MAP_FAILED && sh.map_size)
         munmap(sh.map_result, sh.map_size);
     memset(&sh, 0, sizeof(sh));
 }