diff --git a/minui/graphics_adf.cpp b/minui/graphics_adf.cpp
index 17f30d1..9ab0b06 100644
--- a/minui/graphics_adf.cpp
+++ b/minui/graphics_adf.cpp
@@ -67,8 +67,9 @@
   surf->base.data = static_cast<uint8_t*>(mmap(nullptr, surf->pitch * surf->base.height, PROT_WRITE,
                                                MAP_SHARED, surf->fd, surf->offset));
   if (surf->base.data == MAP_FAILED) {
+    int saved_errno = errno;
     close(surf->fd);
-    return -errno;
+    return -saved_errno;
   }
 
   return 0;