diff --git a/packages/excubiae/contracts/extensions/SemaphoreExcubia.sol b/packages/excubiae/contracts/extensions/SemaphoreExcubia.sol
index bed1904..9f4ac09 100644
--- a/packages/excubiae/contracts/extensions/SemaphoreExcubia.sol
+++ b/packages/excubiae/contracts/extensions/SemaphoreExcubia.sol
@@ -39,7 +39,7 @@ contract SemaphoreExcubia is Excubia {
 
         SEMAPHORE = ISemaphore(_semaphore);
 
-        if (SEMAPHORE.groupCounter() < _groupId) revert InvalidGroup();
+        if (ISemaphore(_semaphore).groupCounter() < _groupId) revert InvalidGroup();
 
         GROUP_ID = _groupId;
     }