diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index 2a7ad792df..147beb78ad 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -2704,6 +2704,13 @@ void ex_delfunction(exarg_T *eap)
     *p = NUL;
   }
 
+  if (isdigit(*name) && fudi.fd_dict == NULL) {
+    if (!eap->skip) {
+      semsg(_(e_invarg2), eap->arg);
+    }
+    xfree(name);
+    return;
+  }
   if (!eap->skip) {
     fp = find_func(name);
   }
diff --git a/src/nvim/testdir/test_user_func.vim b/src/nvim/testdir/test_user_func.vim
index 98c2fdd531..7aa21d7816 100644
--- a/src/nvim/testdir/test_user_func.vim
+++ b/src/nvim/testdir/test_user_func.vim
@@ -423,6 +423,11 @@ func Test_del_func()
   func d.fn()
     return 1
   endfunc
+
+  " cannot delete the dict function by number
+  let nr = substitute(execute('echo d'), '.*function(''\(\d\+\)'').*', '\1', '')
+  call assert_fails('delfunction g:' .. nr, 'E475: Invalid argument: g:')
+
   delfunc d.fn
   call assert_equal({'a' : 10}, d)
 endfunc