diff --git a/src/eval.c b/src/eval.c
index b83334c..b04f330 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -1564,11 +1564,12 @@
  * Returns OK or FAIL.
  */
     int
-call_vim_function(func, argc, argv, safe, rettv)
+call_vim_function(func, argc, argv, safe, str_arg_only, rettv)
     char_u      *func;
     int		argc;
     char_u      **argv;
     int		safe;		/* use the sandbox */
+    int		str_arg_only;	/* all arguments are strings */
     typval_T	*rettv;
 {
     typval_T	*argvars;
@@ -1593,8 +1594,11 @@
 	    continue;
 	}
 
-	/* Recognize a number argument, the others must be strings. */
-	vim_str2nr(argv[i], NULL, &len, TRUE, TRUE, &n, NULL);
+	if (str_arg_only)
+	    len = 0;
+	else
+	    /* Recognize a number argument, the others must be strings. */
+	    vim_str2nr(argv[i], NULL, &len, TRUE, TRUE, &n, NULL);
 	if (len != 0 && len == (int)STRLEN(argv[i]))
 	{
 	    argvars[i].v_type = VAR_NUMBER;
@@ -1646,7 +1650,8 @@
     typval_T	rettv;
     char_u	*retval;
 
-    if (call_vim_function(func, argc, argv, safe, &rettv) == FAIL)
+    /* All arguments are passed as strings, no conversion to number. */
+    if (call_vim_function(func, argc, argv, safe, TRUE, &rettv) == FAIL)
 	return NULL;
 
     retval = vim_strsave(get_tv_string(&rettv));
@@ -1671,7 +1676,8 @@
     typval_T	rettv;
     long	retval;
 
-    if (call_vim_function(func, argc, argv, safe, &rettv) == FAIL)
+    /* All arguments are passed as strings, no conversion to number. */
+    if (call_vim_function(func, argc, argv, safe, TRUE, &rettv) == FAIL)
 	return -1;
 
     retval = get_tv_number_chk(&rettv, NULL);
@@ -1694,7 +1700,8 @@
 {
     typval_T	rettv;
 
-    if (call_vim_function(func, argc, argv, safe, &rettv) == FAIL)
+    /* All arguments are passed as strings, no conversion to number. */
+    if (call_vim_function(func, argc, argv, safe, TRUE, &rettv) == FAIL)
 	return NULL;
 
     if (rettv.v_type != VAR_LIST)