--- a/SignalSet.st	Sun Dec 08 22:03:46 2019 +0100
+++ b/SignalSet.st	Mon Dec 09 11:20:44 2019 +0100
@@ -99,10 +99,12 @@
 
 !SignalSet methodsFor:'adding'!
 
-, anException
-    "add anException to the set"
+, anExceptionHandler
+    "add anExceptionHandler to the set"
 
-    self add:anException
+    self add:anExceptionHandler.
+
+    "Modified: / 09-12-2019 / 11:09:05 / Stefan Vogel"
 !
 
 add:anExceptionHandler
@@ -110,10 +112,20 @@
      Very bad (recursive) things may happen if e.g. #accepts: is called
      and raises a MessageNotUnderstood error."
 
+    anExceptionHandler isNil ifTrue:[
+        "Ignore nil exceptionHandler - it may be due to a missing (not loaded) expception class"    
+        ^ nil.
+    ].
     anExceptionHandler isExceptionHandler ifFalse:[
-	SignalError raiseWith:anExceptionHandler errorString:' - trying to add a non-exceptionHandler to a SignalSet'.
+        SignalError raiseWith:anExceptionHandler errorString:' - trying to add a non-exceptionHandler to a SignalSet'.
     ].
     ^ super add:anExceptionHandler.
+
+   "
+        SignalSet with:nil with:TimeoutError
+   "
+
+    "Modified: / 09-12-2019 / 11:08:56 / Stefan Vogel"
 ! !
 
 !SignalSet methodsFor:'queries'!