diff --git a/src/ray/design_docs/id_specification.md b/src/ray/design_docs/id_specification.md
index baf1aad61..a07fec7c4 100644
--- a/src/ray/design_docs/id_specification.md
+++ b/src/ray/design_docs/id_specification.md
@@ -29,7 +29,7 @@ Ray ID Specification
 #### JobID (2 bytes)
 `JobID` is generated by `GCS` to ensure uniqueness. Its length is 2 bytes.
 
-#### ActorID (8 bytes)
+#### ActorID (6 bytes)
 An `ActorID` contains two parts: 1) 4 unique bytes, and 2) its `JobID`.
 
 #### TaskID (14 bytes)