1 files changed, 5 insertions, 1 deletions
diff --git a/newlib/libc/stdio/fileno.c b/newlib/libc/stdio/fileno.c
index d578c3ede..c9ecbb424 100644
--- a/newlib/libc/stdio/fileno.c
+++ b/newlib/libc/stdio/fileno.c
@@ -35,6 +35,10 @@ int
 _DEFUN (fileno, (f),
 	FILE * f)
 {
+  int result;
+  _flockfile(f);
   CHECK_INIT (f);
-  return __sfileno (f);
+  result = __sfileno (f);
+  _funlockfile(f);
+  return result;
 }