1 files changed, 6 insertions, 1 deletions
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 99e3de7ec..d5bb510ee 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -447,7 +447,12 @@ _lseek (int fd, off_t pos, int dir)
   off_t res;
   sigframe thisframe (mainthread);
 
-  if (fdtab.not_open (fd))
+  if ( dir != SEEK_SET && dir != SEEK_CUR && dir != SEEK_END )
+    {
+      set_errno ( EINVAL );
+      res = -1;
+    }
+  else if (fdtab.not_open (fd))
     {
       set_errno (EBADF);
       res = -1;