diff --git a/lib/SimpleSAML/Auth/State.php b/lib/SimpleSAML/Auth/State.php
index 48a5cfea6d754ba11add3f3d8a946cf19633fb49..9a3efc4cc09cfac6893494e60407e5db775c44c4 100644
--- a/lib/SimpleSAML/Auth/State.php
+++ b/lib/SimpleSAML/Auth/State.php
@@ -83,8 +83,10 @@ class State
 
     /**
      * The URL parameter which contains the exception state id.
+     * Note that this does not contain a "." since it's used in the
+     * _REQUEST superglobal that does not allow dots.
      */
-    const EXCEPTION_PARAM = '\SimpleSAML\Auth\State.exceptionId';
+    const EXCEPTION_PARAM = '\SimpleSAML\Auth\State_exceptionId';
 
 
     /**