diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 0eda5de..ab1dbf3 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -3607,4 +3607,9 @@
   let &encoding = save_enc
 endfunc
 
+func Test_fullcommand()
+  " this used to crash vim
+  call assert_equal('', fullcommand(10))
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab