diff --git a/configure.ac b/configure.ac
index 38c7b61d..94cfe7e3 100644
--- a/configure.ac
+++ b/configure.ac
@@ -20,6 +20,8 @@ AS_IF([test "${ac_cv_prog_cc_c99}" = "no"], [
   AC_MSG_ERROR([No C99 compiler found!])
 ])
 
+AX_APPEND_COMPILE_FLAGS([-Wall -Wextra -Wno-unused-parameter])
+
 AC_SYS_LARGEFILE
 AC_DEFINE([_GNU_SOURCE], 1, [Define to include GNU extensions to POSIX])
 
diff --git a/m4 b/m4
index 2d8eb252..2fc20057 160000
--- a/m4
+++ b/m4
@@ -1 +1 @@
-Subproject commit 2d8eb25218daa933d337df939b2427895b344344
+Subproject commit 2fc2005725541137820d6f8ce09c34bbcae69340