diff --git a/src/WebAPI/Endpoints/WithAuthenticate.php b/src/WebAPI/Endpoints/WithAuthenticate.php
index 677ac6b..973e709 100644
--- a/src/WebAPI/Endpoints/WithAuthenticate.php
+++ b/src/WebAPI/Endpoints/WithAuthenticate.php
@@ -9,10 +9,10 @@ public function token(): string
     {
         $token = getenv('SLACK_API_ACCESS_TOKEN');
 
-        if (!$token) {
+        if ($token === false) {
             throw new \RuntimeException('Require Slack Api Access Token to set env: SLACK_API_ACCESS_TOKEN');
         }
 
         return $token;
     }
-}
\ No newline at end of file
+}
diff --git a/tests/WebAPI/Endpoints/WithAuthenticateTest.php b/tests/WebAPI/Endpoints/WithAuthenticateTest.php
index f774302..69601dd 100644
--- a/tests/WebAPI/Endpoints/WithAuthenticateTest.php
+++ b/tests/WebAPI/Endpoints/WithAuthenticateTest.php
@@ -22,7 +22,7 @@ public function testToken()
      */
     public function testTokenException()
     {
-        putenv('SLACK_API_ACCESS_TOKEN=');
+        putenv('SLACK_API_ACCESS_TOKEN');
         /** @var WithAuthenticate $withAuthenticate */
         $withAuthenticate = $this->getMockForTrait(WithAuthenticate::class);
         $this->expectException(\RuntimeException::class);