diff --git a/examples/Makefile.am b/examples/Makefile.am
index 1f559be..381fdb7 100644
--- a/examples/Makefile.am
+++ b/examples/Makefile.am
@@ -17,4 +17,4 @@ test12_SOURCES = test12.cpp
 
 INCLUDES = -I$(top_srcdir)/include
 
-AM_CXXFLAGS = -Wall
+AM_CXXFLAGS = -Wall -Wextra
diff --git a/include/tclap/Arg.h b/include/tclap/Arg.h
index 4223917..4cdda56 100644
--- a/include/tclap/Arg.h
+++ b/include/tclap/Arg.h
@@ -1,3 +1,4 @@
+// -*- Mode: c++; c-basic-offset: 4; tab-width: 4; -*-
 
 /****************************************************************************** 
  * 
@@ -410,6 +411,7 @@ struct ArgTraits<std::string> {
 template<typename T> void
 ExtractValue(T &destVal, const std::string& strVal, ValueLike vl)
 {
+    static_cast<void>(vl); // Avoid warning about unused vl
     std::istringstream is(strVal);
 
     int valuesRead = 0;
@@ -442,6 +444,7 @@ ExtractValue(T &destVal, const std::string& strVal, ValueLike vl)
 template<typename T> void
 ExtractValue(T &destVal, const std::string& strVal, StringLike sl)
 {
+    static_cast<void>(sl); // Avoid warning about unused sl
     destVal = strVal;
 }
 
diff --git a/include/tclap/DocBookOutput.h b/include/tclap/DocBookOutput.h
index 86f8090..d2f1290 100644
--- a/include/tclap/DocBookOutput.h
+++ b/include/tclap/DocBookOutput.h
@@ -174,8 +174,9 @@ inline void DocBookOutput::usage(CmdLineInterface& _cmd )
 inline void DocBookOutput::failure( CmdLineInterface& _cmd,
 				    ArgException& e ) 
 { 
-		std::cout << e.what() << std::endl;
-		throw ExitException(1);
+	static_cast<void>(_cmd); // unused
+	std::cout << e.what() << std::endl;
+	throw ExitException(1);
 }
 
 inline void DocBookOutput::substituteSpecialChars( std::string& s,
diff --git a/include/tclap/ZshCompletionOutput.h b/include/tclap/ZshCompletionOutput.h
index 2aaff04..1ed4381 100644
--- a/include/tclap/ZshCompletionOutput.h
+++ b/include/tclap/ZshCompletionOutput.h
@@ -1,3 +1,5 @@
+// -*- Mode: c++; c-basic-offset: 4; tab-width: 4; -*-
+
 /****************************************************************************** 
  * 
  *  file:  ZshCompletionOutput.h
@@ -125,6 +127,7 @@ inline void ZshCompletionOutput::usage(CmdLineInterface& _cmd )
 inline void ZshCompletionOutput::failure( CmdLineInterface& _cmd,
 				                ArgException& e )
 {
+	static_cast<void>(_cmd); // unused
 	std::cout << e.what() << std::endl;
 }