diff --git a/rdkafka/constants.php b/rdkafka/constants.php
index ca51cc15..c512ee69 100755
--- a/rdkafka/constants.php
+++ b/rdkafka/constants.php
@@ -109,6 +109,7 @@ const RD_KAFKA_CONSUMER = 1;
 const RD_KAFKA_OFFSET_BEGINNING = -2;
 const RD_KAFKA_OFFSET_END = -1;
 const RD_KAFKA_OFFSET_STORED = -1000;
+const RD_KAFKA_OFFSET_INVALID = -1001;
 const RD_KAFKA_PARTITION_UA = -1;
 const RD_KAFKA_PRODUCER = 0;
 const RD_KAFKA_VERSION = 722687;