diff --git a/linux-user/flatload.c b/linux-user/flatload.c
index 42d1079..a35a560 100644
--- a/linux-user/flatload.c
+++ b/linux-user/flatload.c
@@ -95,7 +95,13 @@
     int ret;
 
     buf = lock_user(VERIFY_WRITE, ptr, len, 0);
+    if (!buf) {
+        return -EFAULT;
+    }
     ret = pread(fd, buf, len, offset);
+    if (ret < 0) {
+        ret = -errno;
+    }
     unlock_user(buf, ptr, len);
     return ret;
 }