diff --git a/src/dumm/Makefile.am b/src/dumm/Makefile.am
index 64e40ee63..873ff21c7 100644
--- a/src/dumm/Makefile.am
+++ b/src/dumm/Makefile.am
@@ -17,3 +17,16 @@ irdumm_LDADD = libdumm.la -lruby1.8
 INCLUDES = -I$(top_srcdir)/src/libstrongswan ${gtk_CFLAGS} \
   ${RUBYINCLUDE}
 AM_CFLAGS = -D_FILE_OFFSET_BITS=64
+
+all-local: ext
+
+clean-local:
+	(test -f ext/Makefile && cd ext && $(MAKE) clean && rm Makefile || true)
+
+install-data-local:
+	(test -f ext/Makefile && cd ext && $(MAKE) install)
+
+ext:	libdumm.la
+	(cd ext && $(RUBY) extconf.rb && $(MAKE))
+
+.PHONY: ext
diff --git a/src/dumm/ext/dumm.c b/src/dumm/ext/dumm.c
index 3c860bb68..f7caf252d 100644
--- a/src/dumm/ext/dumm.c
+++ b/src/dumm/ext/dumm.c
@@ -28,6 +28,7 @@
 #undef PACKAGE_TARNAME
 #undef PACKAGE_VERSION
 #undef PACKAGE_STRING
+#undef PACKAGE_BUGREPORT
 #include <ruby.h>
 
 static dumm_t *dumm;
diff --git a/src/dumm/ext/extconf.rb.in b/src/dumm/ext/extconf.rb.in
index 658ab1f7d..36536ec52 100644
--- a/src/dumm/ext/extconf.rb.in
+++ b/src/dumm/ext/extconf.rb.in
@@ -5,6 +5,7 @@
 require 'mkmf'
 
 $defs << " @DEFS@"
+$CFLAGS << " -Wno-format"
 
 dir_config('dumm', '@top_srcdir@/src/dumm', '../.libs')
 dir_config('strongswan', '@top_srcdir@/src/libstrongswan', '../../libstrongswan/.libs')