--- a/JavaVM.st	Wed Nov 30 17:46:38 2016 +0100
+++ b/JavaVM.st	Wed Nov 30 17:47:31 2016 +0100
@@ -3683,6 +3683,9 @@
     | exClass  ex |
 
     exClass := self classForName: aJavaExceptionClassName asSlashedJavaClassName definedBy: nil.
+    exClass isNil ifTrue:[
+        self error:'Missing Java Exception Class: ', aJavaExceptionClassName.
+    ].
     ex := exClass newWith_String: someMessage.
     ^ self throwException: ex