diff --git a/tests/test_signatures.py b/tests/test_signatures.py
index 465e645..9c2a996 100644
--- a/tests/test_signatures.py
+++ b/tests/test_signatures.py
@@ -233,6 +233,9 @@ def test_store_signatures_with_different_digests(
 
     # Mock get_last_log_index
     mocker.patch(
+    # Call store_signatures
+    with pytest.raises(errors.SignatureMismatch):
+        store_signatures(signatures, image_digest, TEST_PUBKEY_PATH)
         "dangerzone.updater.signatures.get_last_log_index",
         return_value=50,
     )