diff --git a/src/eval.c b/src/eval.c
index 99b3bba..f9db2f9 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -12940,6 +12940,7 @@
 		int	xp_namelen;
 		long	argt;
 
+		/* input() with a third argument: completion */
 		rettv->vval.v_string = NULL;
 
 		xp_name = get_tv_string_buf_chk(&argvars[2], buf);
@@ -12958,6 +12959,11 @@
 	    rettv->vval.v_string =
 		getcmdline_prompt(inputsecret_flag ? NUL : '@', p, echo_attr,
 				  xp_type, xp_arg);
+	if (rettv->vval.v_string == NULL
+		&& argvars[1].v_type != VAR_UNKNOWN
+		&& argvars[2].v_type != VAR_UNKNOWN)
+	    rettv->vval.v_string = vim_strsave(get_tv_string_buf(
+							   &argvars[2], buf));
 
 	vim_free(xp_arg);