diff --git a/configure.ac b/configure.ac
index a14bcfe..f3db651 100644
--- a/configure.ac
+++ b/configure.ac
@@ -99,6 +99,7 @@ solaris*)
 *freebsd*)
 	xenable_intf_imb=no
 	xenable_intf_lipmi=no
+	CFLAGS="$CFLAGS -D__BSD_VISIBLE"
 	;;
 *netbsd*)
 	xenable_intf_imb=no
diff --git a/src/plugins/open/open.c b/src/plugins/open/open.c
index df56172..5beeac7 100644
--- a/src/plugins/open/open.c
+++ b/src/plugins/open/open.c
@@ -29,7 +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
+#define _POSIX_C_SOURCE 1
 
 #include <stdio.h>
 #include <fcntl.h>
diff --git a/src/plugins/serial/serial_basic.c b/src/plugins/serial/serial_basic.c
index e3322c1..57ac84a 100644
--- a/src/plugins/serial/serial_basic.c
+++ b/src/plugins/serial/serial_basic.c
@@ -33,7 +33,9 @@
 
 /* Serial Interface, Basic Mode plugin. */
 
+#if defined HAVE_ALLOCA_H
 #include <alloca.h>
+#endif
 #include <stdio.h>
 #include <fcntl.h>
 #include <time.h>
diff --git a/src/plugins/serial/serial_terminal.c b/src/plugins/serial/serial_terminal.c
index cd33422..8fe6a75 100644
--- a/src/plugins/serial/serial_terminal.c
+++ b/src/plugins/serial/serial_terminal.c
@@ -33,7 +33,9 @@
 
 /* Serial Interface, Terminal Mode plugin. */
 
+#if defined HAVE_ALLOCA_H
 #include <alloca.h>
+#endif
 #include <stdio.h>
 #include <fcntl.h>
 #include <unistd.h>