diff --git a/cf/roken-frag.m4 b/cf/roken-frag.m4
index c52df933e..b3419a6fc 100644
--- a/cf/roken-frag.m4
+++ b/cf/roken-frag.m4
@@ -72,6 +72,7 @@ AC_CHECK_HEADERS([\
 	rpcsvc/dbm.h				\
 	rpcsvc/ypclnt.h				\
 	shadow.h				\
+	sys/bswap.h				\
 	sys/ioctl.h				\
 	sys/param.h				\
 	sys/proc.h				\
@@ -243,6 +244,16 @@ AC_NEED_PROTO([
 vasnprintf)dnl
 fi
 
+AC_FIND_FUNC_NO_LIBS(bswap16,,
+[#ifdef HAVE_SYS_BSWAP_H
+#include <sys/bswap.h>
+#endif],0)
+
+AC_FIND_FUNC_NO_LIBS(bswap32,,
+[#ifdef HAVE_SYS_BSWAP_H
+#include <sys/bswap.h>
+#endif],0)
+
 AC_FIND_FUNC_NO_LIBS(pidfile,util,
 [#ifdef HAVE_UTIL_H
 #include <util.h>