diff --git a/src/interceptors/oauth-interceptor.js b/src/interceptors/oauth-interceptor.js
index b94be80..f411396 100644
--- a/src/interceptors/oauth-interceptor.js
+++ b/src/interceptors/oauth-interceptor.js
@@ -9,7 +9,11 @@ function oauthInterceptor($q, $rootScope, OAuthToken) {
       config.headers = config.headers || {};
 
       // Inject `Authorization` header.
-      if (!config.headers.hasOwnProperty('Authorization') && OAuthToken.getAuthorizationHeader()) {
+      if (
+        (
+          !config.headers.hasOwnProperty('Authorization') || typeof config.headers.Authorization !== 'undefined'
+        ) && OAuthToken.getAuthorizationHeader()
+      ) {
         config.headers.Authorization = OAuthToken.getAuthorizationHeader();
       }