diff --git a/linux-user/flatload.c b/linux-user/flatload.c
index 04d8138..0e4be5b 100644
--- a/linux-user/flatload.c
+++ b/linux-user/flatload.c
@@ -487,7 +487,10 @@
     stack_len += (bprm->envc + 1) * 4; /* the envp array */
 
 
+    mmap_lock();
     res = load_flat_file(bprm, libinfo, 0, &stack_len);
+    mmap_unlock();
+
     if (is_error(res)) {
             return res;
     }