diff --git a/configure.ac b/configure.ac
index 025b91214..0c84bbca9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -313,6 +313,7 @@ case $host_cpu in
 	case $host_os in
 		*linux*)	DEFAULT_INT10=vm86 ;;
 		*freebsd*)	AC_DEFINE(USE_DEV_IO) ;;
+		*dragonfly*)	AC_DEFINE(USE_DEV_IO) ;;
 		*netbsd*)	AC_DEFINE(USE_I386_IOPL)
 				SYS_LIBS=-li386
 				;;
@@ -337,6 +338,7 @@ case $host_cpu in
 	I386_VIDEO=yes
 	case $host_os in
 		*freebsd*)	AC_DEFINE(USE_DEV_IO, 1, [BSD /dev/io]) ;;
+		*dragonfly*)	AC_DEFINE(USE_DEV_IO, 1, [BSD /dev/io]) ;;
 		*netbsd*)	AC_DEFINE(USE_I386_IOPL, 1, [BSD i386 iopl])
 				SYS_LIBS=-lx86_64
 				;;
@@ -367,7 +369,7 @@ DRI2=no
 KDRIVE_HW=no
 dnl it would be nice to autodetect these *CONS_SUPPORTs
 case $host_os in
-  *freebsd*)
+  *freebsd* | *dragonfly*)
 	case $host_os in
 		kfreebsd*-gnu) ;;
 		*) AC_DEFINE(CSRG_BASED, 1, [System is BSD-like]) ;;
@@ -1360,7 +1362,7 @@ if test "x$XORG" = xyes -o "x$XGL" = xyes; then
 			;;
 		esac
 		;;
-	  freebsd* | kfreebsd*-gnu)
+	  freebsd* | kfreebsd*-gnu | dragonfly*)
 	  	XORG_OS="freebsd"
 		XORG_OS_SUBDIR="bsd"
 		xorg_bus_bsdpci="yes"