diff --git a/src/keycloak/openid_connection.py b/src/keycloak/openid_connection.py
index 081cbaf..96ea296 100644
--- a/src/keycloak/openid_connection.py
+++ b/src/keycloak/openid_connection.py
@@ -114,19 +114,18 @@ class KeycloakOpenIDConnection(ConnectionManager):
         self.client_secret_key = client_secret_key
         self.user_realm_name = user_realm_name
         self.timeout = timeout
+        self.headers = {}
+        self.custom_headers = custom_headers
 
         if self.token is None:
             self.get_token()
 
-        self.headers = (
-            {
+        if self.token is not None:
+            self.headers = {
+                **self.headers,
                 "Authorization": "Bearer " + self.token.get("access_token"),
-                "Content-Type": "application/json",
+                "Content-Type": "application/json"
             }
-            if self.token is not None
-            else {}
-        )
-        self.custom_headers = custom_headers
 
         super().__init__(
             base_url=self.server_url, headers=self.headers, timeout=60, verify=self.verify