diff --git a/src/strings.c b/src/strings.c
index 710b1d3..33616d6 100644
--- a/src/strings.c
+++ b/src/strings.c
@@ -2801,7 +2801,7 @@
 
 	if (ap_types == NULL || ap_types[*arg_cur] == NULL)
 	{
-	    siemsg(e_aptypes_is_null_str_nr, fmt, *arg_cur);
+	    siemsg(e_aptypes_is_null_nr_str, *arg_cur, fmt);
 	    return;
 	}