diff --git a/app/modules/ws2p/lib/constants.ts b/app/modules/ws2p/lib/constants.ts
index b57598b7bbe327066124970f0469d33a9df9f9c6..84bda573fd1f43d4a19ba45bb1ff8735ef9997e5 100644
--- a/app/modules/ws2p/lib/constants.ts
+++ b/app/modules/ws2p/lib/constants.ts
@@ -52,7 +52,7 @@ export const WS2PConstants = {
     + CommonConstants.FORMATS.BLOCKSTAMP
     + '$'),
 
-  HEAD_V1_REGEXP: new RegExp('^WS2P(?:O[CT][SAM])?(?:I[CT])?:HEAD:1:'
+  HEAD_V1_REGEXP: new RegExp('^WS2P(?:O[CT][SAM]?)?(?:I[CT])?:HEAD:1:'
   + '(' + CommonConstants.FORMATS.PUBKEY + '):'
   + '(' + CommonConstants.FORMATS.BLOCKSTAMP + '):'
   + '(' + CommonConstants.FORMATS.WS2PID + '):'
@@ -61,7 +61,7 @@ export const WS2PConstants = {
   + '(' + CommonConstants.FORMATS.POW_PREFIX + ')'
   + '$'),
 
-  HEAD_V2_REGEXP: new RegExp('^WS2P(?:O[CT][SAM])?(?:I[CT])?:HEAD:2:'
+  HEAD_V2_REGEXP: new RegExp('^WS2P(?:O[CT][SAM]?)?(?:I[CT])?:HEAD:2:'
   + '(' + CommonConstants.FORMATS.PUBKEY + '):'
   + '(' + CommonConstants.FORMATS.BLOCKSTAMP + '):'
   + '(' + CommonConstants.FORMATS.WS2PID + '):'