diff --git a/spec/core.md b/spec/core.md
index c52bb21..97a2cb2 100644
--- a/spec/core.md
+++ b/spec/core.md
@@ -620,7 +620,7 @@ A convenient regex to match `peer` DIDs is:
 
 ::: example Matching regex
 ``` text
-^did:peer:(([01](z)([1-9a-km-zA-HJ-NP-Z]{46,47}))|(2((\.[AEVID](z)([1-9a-km-zA-HJ-NP-Z]{46,47}))+(\.(S)[0-9a-zA-Z=]*)?)))$
+^did:peer:(([01](z)([1-9a-km-zA-HJ-NP-Z]{46,47}))|(2((\.[AEVID](z)([1-9a-km-zA-HJ-NP-Z]{46,47}))+(\.(S)[0-9a-zA-Z=]*)*)))$
 ```
 :::