diff --git a/ps/sortformat.c b/ps/sortformat.c
index 9fb1a567..fd918a20 100644
--- a/ps/sortformat.c
+++ b/ps/sortformat.c
@@ -315,7 +315,8 @@ static const char *format_parse(sf_node *sfn){
   if(0) improper: err=_("improper format list");
   if(0) badwidth: err=_("column widths must be unsigned decimal numbers");
   if(0) notmacro: err=_("can not set width for a macro (multi-column) format specifier");
-  if(strchr(sfn->sf,'%')) err = aix_format_parse(sfn);
+  if (!err)
+    if(strchr(sfn->sf,'%')) err = aix_format_parse(sfn);
   return err;
 }