diff --git a/lib/Utils/OAuth2.php b/lib/Utils/OAuth2.php
index 6823a4fa1..9d8c33748 100644
--- a/lib/Utils/OAuth2.php
+++ b/lib/Utils/OAuth2.php
@@ -18,11 +18,19 @@ class OAuth2
      */
     public static function getAuthUrl(string $clientId, string $redirectURI, array $scopesArray = [], array $optionalScopesArray = [])
     {
-        return static::AUTHORIZE_URL.'?'.http_build_query([
+        $queryParams = [
             'client_id' => $clientId,
             'redirect_uri' => $redirectURI,
-            'scope' => implode(' ', $scopesArray),
-            'optional_scope' => implode(' ', $optionalScopesArray),
-        ], '', '&', PHP_QUERY_RFC3986);
+        ];
+
+        if (!empty($scopesArray)) {
+            $queryParams['scope'] = implode(' ', $scopesArray);
+        }
+
+        if (!empty($optionalScopesArray)) {
+            $queryParams['optional_scope'] = implode(' ', $optionalScopesArray);
+        }
+
+        return static::AUTHORIZE_URL.'?'.http_build_query($queryParams, '', '&', PHP_QUERY_RFC3986);
     }
 }
diff --git a/tests/Unit/Utils/OAuth2Test.php b/tests/Unit/Utils/OAuth2Test.php
index 13967dc15..12cacc67f 100644
--- a/tests/Unit/Utils/OAuth2Test.php
+++ b/tests/Unit/Utils/OAuth2Test.php
@@ -25,4 +25,18 @@ public function buildAuthorizationUrl()
             $authUrl
         );
     }
+
+    /** @test */
+    public function buildAuthorizationUrlWithEmptyOptionalScope()
+    {
+        $authUrl = OAuth2::getAuthUrl(
+            'clientid',
+            'http://localhost',
+            ['contacts', 'timeline']
+        );
+        $this->assertSame(
+            'https://app.hubspot.com/oauth/authorize?client_id=clientid&redirect_uri=http%3A%2F%2Flocalhost&scope=contacts%20timeline',
+            $authUrl
+        );
+    }
 }