diff --git a/src/Repositories/ClaimSetRepositoryInterface.php b/src/Repositories/ClaimSetRepositoryInterface.php
index 7c21bf3..acd99a7 100644
--- a/src/Repositories/ClaimSetRepositoryInterface.php
+++ b/src/Repositories/ClaimSetRepositoryInterface.php
@@ -8,5 +8,5 @@
 
 interface ClaimSetRepositoryInterface
 {
-    public function getClaimSetByScopeIdentifier($scopeIdentifier);
+    public function getClaimSetByScopeIdentifier(string $scopeIdentifier);
 }
diff --git a/src/Repositories/IdentityProviderInterface.php b/src/Repositories/IdentityProviderInterface.php
index 2074ca5..1032a9b 100644
--- a/src/Repositories/IdentityProviderInterface.php
+++ b/src/Repositories/IdentityProviderInterface.php
@@ -14,5 +14,5 @@ interface IdentityProviderInterface extends RepositoryInterface
     /**
      * @return UserEntityInterface&ClaimSetInterface
      */
-    public function getUserEntityByIdentifier($identifier);
+    public function getUserEntityByIdentifier(string $identifier);
 }