diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 65c872d..e017efb 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -13,7 +13,7 @@ jobs:
             fail-fast: false
             matrix:
                 os: [ubuntu-latest]
-                php: ['5.4', '5.5', '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0']
+                php: ['5.4', '5.5', '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3']
 
         steps:
             - name: Checkout
diff --git a/src/OAuth1.php b/src/OAuth1.php
index 8074c6c..1b79de4 100644
--- a/src/OAuth1.php
+++ b/src/OAuth1.php
@@ -335,6 +335,8 @@ public function signRequest($request, $token = null)
      */
     protected function composeSignatureBaseString($method, $url, array $params)
     {
+        $url = isset($url) ? $url : '';
+
         if (strpos($url, '?') !== false) {
             list($url, $queryString) = explode('?', $url, 2);
             parse_str($queryString, $urlParams);
@@ -342,6 +344,9 @@ protected function composeSignatureBaseString($method, $url, array $params)
         }
         unset($params['oauth_signature']);
         uksort($params, 'strcmp'); // Parameters are sorted by name, using lexicographical byte value ordering. Ref: Spec: 9.1.1
+
+        $method = isset($method) ? $method : '';
+
         $parts = [
             strtoupper($method),
             $url,
@@ -359,15 +364,17 @@ protected function composeSignatureBaseString($method, $url, array $params)
      */
     protected function composeSignatureKey($token = null)
     {
+
         $signatureKeyParts = [
-            $this->consumerSecret
+            isset($this->consumerSecret) ? $this->consumerSecret : ''
         ];
 
         if ($token === null) {
             $token = $this->getAccessToken();
         }
         if (is_object($token)) {
-            $signatureKeyParts[] = $token->getTokenSecret();
+            $ts = $token->getTokenSecret();
+            $signatureKeyParts[] = isset($ts)? $ts: '';
         } else {
             $signatureKeyParts[] = '';
         }