diff --git a/index.js b/index.js
index c502735..cc6e827 100644
--- a/index.js
+++ b/index.js
@@ -133,7 +133,7 @@ module.exports = {
     'block-spacing': ['error', 'always'],
     'brace-style': ['error', 'stroustrup', { allowSingleLine: true }],
     camelcase: 'off',
-    'id-match': ['error', '^[a-z][a-z-]*$', { onlyDeclarations: true }],
+    'id-match': ['error', '^[a-z][a-z_]*$', { onlyDeclarations: true }],
     'comma-dangle': ['error', 'never'],
     'comma-spacing': 'error',
     'comma-style': 'error',