diff -up ext/date/lib/parse_iso_intervals.c.old ext/date/lib/parse_iso_intervals.c
--- a/ext/date/lib/parse_iso_intervals.c.old	2013-11-08 18:22:12.225586458 +0100
+++ b/ext/date/lib/parse_iso_intervals.c	2013-11-08 18:22:47.484721897 +0100
@@ -380,7 +380,7 @@ yy6:
 					break;
 			}
 			ptr++;
-		} while (*ptr);
+		} while (!s->errors->error_count && *ptr);
 		s->have_period = 1;
 		TIMELIB_DEINIT;
 		return TIMELIB_PERIOD;
diff -up ext/date/lib/parse_iso_intervals.re.old ext/date/lib/parse_iso_intervals.re
--- a/ext/date/lib/parse_iso_intervals.re.old	2013-11-08 18:09:18.815549958 +0100
+++ b/ext/date/lib/parse_iso_intervals.re	2013-11-08 18:09:34.461608419 +0100
@@ -348,7 +348,7 @@ isoweek          = year4 "-"? "W" weekof
 					break;
 			}
 			ptr++;
-		} while (*ptr);
+		} while (!s->errors->error_count && *ptr);
 		s->have_period = 1;
 		TIMELIB_DEINIT;
 		return TIMELIB_PERIOD;