diff --git a/tests/test_jsonschema/test_json_schema_common.py b/tests/test_jsonschema/test_json_schema_common.py
index 9b39e1c..9e2a8f5 100644
--- a/tests/test_jsonschema/test_json_schema_common.py
+++ b/tests/test_jsonschema/test_json_schema_common.py
@@ -1,4 +1,10 @@
+import pytest
+
 from mashumaro.config import BaseConfig
+from mashumaro.jsonschema.models import (
+    JSONSchemaStringFormat,
+    _deserialize_json_schema_instance_format,
+)
 from mashumaro.jsonschema.schema import Instance
 
 
@@ -9,3 +15,12 @@ def test_instance_get_configs():
 
     derived = instance.derive()
     assert derived.get_self_config() is instance.get_self_config()
+
+
+def test_deserialize_json_schema_instance_format():
+    assert (
+        _deserialize_json_schema_instance_format("email")
+        is JSONSchemaStringFormat.EMAIL
+    )
+    with pytest.raises(ValueError):
+        assert _deserialize_json_schema_instance_format("foobar")