diff --git a/configure.in b/configure.in
index 586776e3..d81baae0 100644
--- a/configure.in
+++ b/configure.in
@@ -406,7 +406,7 @@ case "$target" in
        AC_DEFINE(MACOSX, 1, [Compiling on Mac OS X])
        LIBS="$LIBS -framework AudioUnit"
        ;;
-    *-*-freebsd* | *-*-linux*)
+    *-*-freebsd* | *-*-linux* | *-*-dragonfly* | *-*-netbsd* | *-*-openbsd*)
        AC_DEFINE(LINUX, 1, [Compiling on GNU/Linux or *BSD])
        AC_DEFINE(C_DIRECTSERIAL, 1, [ Define to 1 if you want serial passthrough support (Win32, Posix and OS/2).])
        ;;