diff --git a/cf/roken-frag.m4 b/cf/roken-frag.m4
index 452c4fd07..f22b43a5d 100644
--- a/cf/roken-frag.m4
+++ b/cf/roken-frag.m4
@@ -272,6 +272,14 @@ AC_FIND_FUNC_NO_LIBS(bswap32,,
 #include <sys/bswap.h>
 #endif],0)
 
+AC_FIND_FUNC_NO_LIBS(bswap64,,
+[#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#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>
diff --git a/lib/roken/bswap.c b/lib/roken/bswap.c
index 7f8c1c22b..b0c4248da 100644
--- a/lib/roken/bswap.c
+++ b/lib/roken/bswap.c
@@ -34,6 +34,23 @@
 #include <config.h>
 #include "roken.h"
 
+#ifndef HAVE_BSWAP64
+
+ROKEN_LIB_FUNCTION uint64_t ROKEN_LIB_CALL
+bswap64 (uint64_t val)
+{
+    return
+        (val & 0xffULL) << 56 |
+	(val & 0xff00ULL) << 40 |
+	(val & 0xff0000ULL) << 24 |
+	(val & 0xff000000ULL) << 8 |
+	(val & 0xff00000000ULL) >> 8 |
+	(val & 0xff0000000000ULL) >> 24 |
+	(val & 0xff000000000000ULL) >> 40 |
+	(val & 0xff00000000000000ULL) >> 56 ;
+}
+#endif
+
 #ifndef HAVE_BSWAP32
 
 ROKEN_LIB_FUNCTION unsigned int ROKEN_LIB_CALL
diff --git a/lib/roken/roken.h.in b/lib/roken/roken.h.in
index 910c79a46..e6b89277b 100644
--- a/lib/roken/roken.h.in
+++ b/lib/roken/roken.h.in
@@ -765,6 +765,11 @@ ROKEN_LIB_FUNCTION void ROKEN_LIB_CALL pidfile (const char*);
 #endif
 #endif
 
+#ifndef HAVE_BSWAP64
+#define bswap64 rk_bswap64
+ROKEN_LIB_FUNCTION uint64_t ROKEN_LIB_CALL bswap64(uint64_t);
+#endif
+
 #ifndef HAVE_BSWAP32
 #define bswap32 rk_bswap32
 ROKEN_LIB_FUNCTION unsigned int ROKEN_LIB_CALL bswap32(unsigned int);
diff --git a/lib/roken/version-script.map b/lib/roken/version-script.map
index 31c942cdc..ed2e16c4f 100644
--- a/lib/roken/version-script.map
+++ b/lib/roken/version-script.map
@@ -38,6 +38,7 @@ HEIMDAL_ROKEN_1.0 {
 		rk_base64_encode;
 		rk_bswap16;
 		rk_bswap32;
+		rk_bswap64;
 		rk_cgetent;
 		rk_cgetstr;
 		rk_cloexec;