1 files changed, 1 insertions, 1 deletions

diff --git a/lib/chaos_calendar/ical_occurrences.c b/lib/chaos_calendar/ical_occurrences.c
index ba63a6a..6515451 100644
--- a/lib/chaos_calendar/ical_occurrences.c
+++ b/lib/chaos_calendar/ical_occurrences.c
@@ -42,7 +42,7 @@ VALUE occurrences( VALUE dtstart, VALUE dtend, char *rrule ) {
 
   struct icalrecurrencetype recur = icalrecurrencetype_from_string( rrule );
   if( icalerrno != ICAL_NO_ERROR ) {
-    printf( "libical error: %i. -- 1\n", icalerrno );
+    rb_raise(rb_eArgError, "Malformed RRule");
     return Qnil;
   }