diff --git a/configure.ac b/configure.ac
index 959a83a189..da56eefa8e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -134,6 +134,12 @@ AC_INIT(configure.ac)
 		    LDFLAGS="${LDFLAGS} -L/usr/local/lib -L/usr/local/lib/libnet11"
 		    e_magic_file="/usr/share/misc/magic"
                     ;;
+           *-*-openbsd5.1)
+                    CFLAGS="${CFLAGS} -D__OpenBSD__ -fgnu89-inline"
+                    CPPFLAGS="${CPPFLAGS} -I/usr/local/include -I/usr/local/include/libnet-1.1"
+                    LDFLAGS="${LDFLAGS} -L/usr/local/lib -I/usr/local/lib/libnet-1.1"
+                    e_magic_file="/usr/local/share/misc/magic.mgc"
+                    ;;
            *-*-openbsd*)
                     CFLAGS="${CFLAGS} -D__OpenBSD__ -fgnu89-inline"
                     CPPFLAGS="${CPPFLAGS} -I/usr/local/include -I/usr/local/include/libnet-1.1"