diff --git a/httpie/output/formatters/colors.py b/httpie/output/formatters/colors.py
index 0d9bd12e2f..3a29a7cb96 100644
--- a/httpie/output/formatters/colors.py
+++ b/httpie/output/formatters/colors.py
@@ -385,4 +385,4 @@ def make_styles():
 
 PIE_STYLES = make_styles()
 PIE_STYLE_NAMES = list(PIE_STYLES.keys())
-BUNDLED_STYLES |= PIE_STYLES.keys()
+BUNDLED_STYLES |= {style.value for style in PIE_STYLES}
diff --git a/tests/test_cli_ui.py b/tests/test_cli_ui.py
index bb744cdc4e..9b7ae3e150 100644
--- a/tests/test_cli_ui.py
+++ b/tests/test_cli_ui.py
@@ -63,3 +63,14 @@ def fake_terminal_size(*args, **kwargs):
 def test_naked_invocation(ignore_terminal_size, args, expected_msg):
     result = http(*args, tolerate_error_exit_status=True)
     assert result.stderr == expected_msg
+
+
+def test_invalid_style_lists_bundled_pie_styles_by_name():
+    result = http(
+        '--style', '$invalid', '--offline', 'pie.dev',
+        tolerate_error_exit_status=True,
+    )
+    assert 'invalid choice' in result.stderr
+    assert 'PieStyle' not in result.stderr
+    for name in ('pie', 'pie-dark', 'pie-light'):
+        assert name in result.stderr