diff --git a/src/lib/src/Makefile.am b/src/lib/src/Makefile.am
index 3f8764e..288ecad 100644
--- a/src/lib/src/Makefile.am
+++ b/src/lib/src/Makefile.am
@@ -2,7 +2,7 @@ AM_CPPFLAGS = \
 	-I$(top_srcdir)/src/lib/include \
 	-I$(top_srcdir)/src/acpica/source/include \
 	-I$(top_srcdir)/src/acpica/source/compiler \
-	-Wall -Werror
+	-Wall -Werror -Wextra
 
 pkglib_LTLIBRARIES = libfwts.la
 libfwts_la_LDFLAGS = -lpcre -lpthread -ljson -version-info 1:0:0 \