diff --git a/src/eval.c b/src/eval.c
index 445b6b9..a51225d 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -12044,6 +12044,7 @@
 {
     typval_T	rettv;
     typval_T	argv[3];
+    char_u	buf[NUMBUFLEN];
     char_u	*s;
     int		retval = FAIL;
     int		dummy;
@@ -12051,9 +12052,9 @@
     copy_tv(tv, &vimvars[VV_VAL].vv_tv);
     argv[0] = vimvars[VV_KEY].vv_tv;
     argv[1] = vimvars[VV_VAL].vv_tv;
-    s = expr->vval.v_string;
     if (expr->v_type == VAR_FUNC)
     {
+	s = expr->vval.v_string;
 	if (call_func(s, (int)STRLEN(s),
 		    &rettv, 2, argv, 0L, 0L, &dummy, TRUE, NULL, NULL) == FAIL)
 	    goto theend;
@@ -12070,6 +12071,9 @@
     }
     else
     {
+	s = get_tv_string_buf_chk(expr, buf);
+	if (s == NULL)
+	    goto theend;
 	s = skipwhite(s);
 	if (eval1(&s, &rettv, TRUE) == FAIL)
 	    goto theend;