diff --git a/configure.ac b/configure.ac
index 282b3990..ea2f1ab7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -98,6 +98,7 @@ CFLAGS="$CFLAGS"
 AC_PROG_CC_C99
 AX_CHECK_COMPILE_FLAG([-xc99],[CFLAGS="$CFLAGS -xc99"],[],[])
 AX_CHECK_COMPILE_FLAG([-Wall],[CFLAGS="$CFLAGS -Wall"],[],[])
+AX_CHECK_COMPILE_FLAG([-Wall],[CFLAGS="$CFLAGS -Wextra"],[],[])
 
 case "$host_os" in
   linux* ) CFLAGS="$CFLAGS -D_BSD_SOURCE -D_DEFAULT_SOURCE"