diff --git a/src/index.js b/src/index.js
index 5bf8118..74abea0 100644
--- a/src/index.js
+++ b/src/index.js
@@ -3,11 +3,13 @@
 // PushAdapter, it uses GCM for android push, APNS for ios push.
 // WEB for web push.
 import log from 'npmlog';
+import { booleanParser } from './utils.js';
 
-/* istanbul ignore if */
-if (process.env.VERBOSE || process.env.VERBOSE_PARSE_SERVER_PUSH_ADAPTER) {
+/* c8 ignore start */
+if (booleanParser(process.env.VERBOSE || process.env.VERBOSE_PARSE_SERVER_PUSH_ADAPTER)) {
   log.level = 'verbose';
 }
+/* c8 ignore stop */
 
 import ParsePushAdapter from './ParsePushAdapter.js';
 import GCM from './GCM.js';
diff --git a/src/utils.js b/src/utils.js
new file mode 100644
index 0000000..01fc659
--- /dev/null
+++ b/src/utils.js
@@ -0,0 +1,10 @@
+function booleanParser(opt) {
+  if (opt == true || opt == 'true' || opt == '1') {
+    return true;
+  }
+  return false;
+}
+
+export {
+  booleanParser,
+}