diff --git a/src/os/unix/ngx_files.c b/src/os/unix/ngx_files.c
index d4bf043..2154bed 100644
--- a/src/os/unix/ngx_files.c
+++ b/src/os/unix/ngx_files.c
@@ -406,7 +406,7 @@
     flags = fcntl(fd, F_GETFL);
 
     if (flags == -1) {
-        return -1;
+        return NGX_FILE_ERROR;
     }
 
     return fcntl(fd, F_SETFL, flags | O_DIRECT);
@@ -421,7 +421,7 @@
     flags = fcntl(fd, F_GETFL);
 
     if (flags == -1) {
-        return -1;
+        return NGX_FILE_ERROR;
     }
 
     return fcntl(fd, F_SETFL, flags & ~O_DIRECT);