diff --git a/pre_commit/clientlib/validate_manifest.py b/pre_commit/clientlib/validate_manifest.py
index 0bfb4a5a..e80e2f95 100644
--- a/pre_commit/clientlib/validate_manifest.py
+++ b/pre_commit/clientlib/validate_manifest.py
@@ -31,9 +31,9 @@ def additional_manifest_check(obj):
     for hook_config in obj:
         language = hook_config['language']
 
-        if not any(language.startswith(lang) for lang in all_languages):
+        if language not in all_languages:
             raise InvalidManifestError(
-                'Expected language {0} for {1} to start with one of {2!r}'.format(
+                'Expected language {0} for {1} to be one of {2!r}'.format(
                     hook_config['id'],
                     hook_config['language'],
                     all_languages,
diff --git a/tests/clientlib/validate_manifest_test.py b/tests/clientlib/validate_manifest_test.py
index ecacf10f..de8e01ac 100644
--- a/tests/clientlib/validate_manifest_test.py
+++ b/tests/clientlib/validate_manifest_test.py
@@ -27,14 +27,25 @@ def test_additional_manifest_check_raises_for_bad_language():
         additional_manifest_check([{'id': 'foo', 'language': 'not valid'}])
 
 
-@pytest.mark.parametrize(('obj'), (
-    [{'language': 'python'}],
-    [{'language': 'ruby'}],
-))
+@pytest.mark.parametrize(
+    'obj', ([{'language': 'python'}], [{'language': 'ruby'}]),
+)
 def test_additional_manifest_check_languages(obj):
     additional_manifest_check(obj)
 
 
+@pytest.mark.parametrize(
+    'obj',
+    (
+        [{'id': 'a', 'language': 'not a language'}],
+        [{'id': 'a', 'language': 'python3'}],
+    ),
+)
+def test_additional_manifest_check_languages_failing(obj):
+    with pytest.raises(InvalidManifestError):
+        additional_manifest_check(obj)
+
+
 @pytest.mark.parametrize(('manifest_obj', 'expected'), (
     ([], False),
     ([{'id': 'a', 'name': 'b', 'entry': 'c', 'language': 'python'}], True),