diff --git a/include/tclap/DocBookOutput.h b/include/tclap/DocBookOutput.h
index a42ca27..f4ac34d 100644
--- a/include/tclap/DocBookOutput.h
+++ b/include/tclap/DocBookOutput.h
@@ -68,6 +68,7 @@ class DocBookOutput : public CmdLineOutput
 		virtual void failure(CmdLineInterface& c, 
 						     ArgException& e );
 
+	    DocBookOutput() : theDelimiter('=') {}
 	protected:
 
 		/**