diff --git a/src/testdir/test_writefile.vim b/src/testdir/test_writefile.vim
index b8e0001..672ddd3 100644
--- a/src/testdir/test_writefile.vim
+++ b/src/testdir/test_writefile.vim
@@ -105,6 +105,10 @@
   if !has('unix')
     return
   endif
-  " Just check that this doesn't cause an error.
-  call writefile(['one'], '/dev/stdout')
+  if filewritable('/dev/stdout')
+    " Just check that this doesn't cause an error.
+    call writefile(['one'], '/dev/stdout')
+  else
+    throw 'Skipped: /dev/stdout is not writable'
+  endif
 endfunc