diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 1ca5424736..51d0847bc7 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -3419,6 +3419,7 @@ static void ins_compl_fixRedoBufForLeader(char_u *ptr_arg)
     else
       return;        /* nothing to do */
   }
+  assert(ptr != NULL);
   if (compl_orig_text != NULL) {
     p = compl_orig_text;
     for (len = 0; p[len] != NUL && p[len] == ptr[len]; ++len)