diff --git a/configure.ac b/configure.ac
index 9df7813..d7c5620 100644
--- a/configure.ac
+++ b/configure.ac
@@ -32,7 +32,7 @@ AC_CHECK_FUNCS([alarm gethostbyname getaddrinfo getifaddrs socket select])
 AC_CHECK_FUNCS([memmove memset strchr strdup strerror])
 AC_CHECK_FUNCS([getpassphrase])
 
-CFLAGS="$CFLAGS -fno-strict-aliasing -Wreturn-type"
+CFLAGS="$CFLAGS -Wall -Wextra -std=c99 -pedantic -Wformat -Wformat-nonliteral"
 
 AM_PROG_LIBTOOL
 LIBTOOL="$LIBTOOL --silent"
diff --git a/lib/helper.c b/lib/helper.c
index f6c0f75..600bfa0 100644
--- a/lib/helper.c
+++ b/lib/helper.c
@@ -29,6 +29,7 @@
  * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  */
+#define _POSIX_SOURCE
 
 #include <sys/types.h>
 #include <sys/stat.h>
diff --git a/lib/ipmi_main.c b/lib/ipmi_main.c
index 724a99a..26f3457 100644
--- a/lib/ipmi_main.c
+++ b/lib/ipmi_main.c
@@ -29,6 +29,7 @@
  * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  */
+#define _XOPEN_SOURCE 700
 
 #include <stdlib.h>
 #include <stdio.h>
diff --git a/lib/ipmi_tsol.c b/lib/ipmi_tsol.c
index de930c9..cae0a51 100644
--- a/lib/ipmi_tsol.c
+++ b/lib/ipmi_tsol.c
@@ -29,6 +29,7 @@
  * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  */
+#define _DEFAULT_SOURCE
 
 #include <sys/types.h>
 #include <sys/stat.h>
diff --git a/src/ipmievd.c b/src/ipmievd.c
index f940579..02c1849 100644
--- a/src/ipmievd.c
+++ b/src/ipmievd.c
@@ -29,6 +29,7 @@
  * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  */
+#define _XOPEN_SOURCE 700
 
 #include <stdio.h>
 #include <fcntl.h>
diff --git a/src/plugins/ipmi_intf.c b/src/plugins/ipmi_intf.c
index a84237e..542b9ec 100644
--- a/src/plugins/ipmi_intf.c
+++ b/src/plugins/ipmi_intf.c
@@ -29,6 +29,8 @@
  * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  */
+#define _XOPEN_SOURCE 700
+#define _GNU_SOURCE 1
 
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/src/plugins/lan/lan.c b/src/plugins/lan/lan.c
index dd90706..6f556e1 100644
--- a/src/plugins/lan/lan.c
+++ b/src/plugins/lan/lan.c
@@ -29,12 +29,15 @@
  * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  */
+#define _POSIX_SOURCE
 
 #include <stdlib.h>
 #include <stdio.h>
 #include <inttypes.h>
 #include <string.h>
+#include <sys/time.h>
 #include <sys/types.h>
+#include <sys/select.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
@@ -248,7 +251,8 @@ static struct ipmi_rs *
 ipmi_lan_recv_packet(struct ipmi_intf * intf)
 {
 	static struct ipmi_rs rsp;
-	fd_set read_set, err_set;
+	fd_set read_set;
+	fd_set err_set;
 	struct timeval tmout;
 	int ret;
 
diff --git a/src/plugins/lanplus/lanplus.c b/src/plugins/lanplus/lanplus.c
index 44b9a38..90993d5 100644
--- a/src/plugins/lanplus/lanplus.c
+++ b/src/plugins/lanplus/lanplus.c
@@ -29,12 +29,15 @@
  * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  */
+#define _POSIX_SOURCE
 
 #include <stdlib.h>
 #include <stdio.h>
 #include <inttypes.h>
 #include <string.h>
+#include <sys/time.h>
 #include <sys/types.h>
+#include <sys/select.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
diff --git a/src/plugins/open/open.c b/src/plugins/open/open.c
index f1ea0dd..66bd5bc 100644
--- a/src/plugins/open/open.c
+++ b/src/plugins/open/open.c
@@ -29,6 +29,7 @@
  * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  */
+#define _POSIX_SOURCE
 
 #include <stdio.h>
 #include <fcntl.h>
@@ -38,6 +39,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
+#include <sys/select.h>
 #include <sys/stat.h>
 
 #include <ipmitool/ipmi.h>
diff --git a/src/plugins/serial/serial_basic.c b/src/plugins/serial/serial_basic.c
index 871593f..3439113 100644
--- a/src/plugins/serial/serial_basic.c
+++ b/src/plugins/serial/serial_basic.c
@@ -29,6 +29,7 @@
  * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF PPS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  */
+#define _GNU_SOURCE 1
 
 /* Serial Interface, Basic Mode plugin. */
 
diff --git a/src/plugins/serial/serial_terminal.c b/src/plugins/serial/serial_terminal.c
index 34c6fc5..171d554 100644
--- a/src/plugins/serial/serial_terminal.c
+++ b/src/plugins/serial/serial_terminal.c
@@ -29,6 +29,7 @@
  * LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
  * EVEN IF PPS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
  */
+#define _GNU_SOURCE 1
 
 /* Serial Interface, Terminal Mode plugin. */