diff --git a/library/OAuth1.php b/library/OAuth1.php
index c537f2b252..4746328316 100644
--- a/library/OAuth1.php
+++ b/library/OAuth1.php
@@ -3,8 +3,10 @@
 
 /* Generic exception class
  */
-class OAuthException extends Exception {
-  // pass
+if (!class_exists('OAuthException', false)) {
+  class OAuthException extends Exception {
+    // pass
+  }
 }
 
 class OAuthConsumer {