diff --git a/sys/mips/include/cpufunc.h b/sys/mips/include/cpufunc.h
index d891b17ba780..5ebaf4cc1720 100644
--- a/sys/mips/include/cpufunc.h
+++ b/sys/mips/include/cpufunc.h
@@ -279,6 +279,13 @@ MIPS_RW32_COP0(entrylo1, MIPS_COP_0_TLB_LO1);
 MIPS_RW32_COP0(prid, MIPS_COP_0_PRID);
 /* XXX 64-bit?  */
 MIPS_RW32_COP0_SEL(ebase, MIPS_COP_0_PRID, 1);
+#ifdef CPU_XBURST
+MIPS_RW32_COP0_SEL(xburst_mbox0, MIPS_COP_0_XBURST_MBOX, 0);
+MIPS_RW32_COP0_SEL(xburst_mbox1, MIPS_COP_0_XBURST_MBOX, 1);
+MIPS_RW32_COP0_SEL(xburst_core_ctl, MIPS_COP_0_XBURST_C12, 2);
+MIPS_RW32_COP0_SEL(xburst_core_sts, MIPS_COP_0_XBURST_C12, 3);
+MIPS_RW32_COP0_SEL(xburst_reim, MIPS_COP_0_XBURST_C12, 4);
+#endif
 MIPS_RW32_COP0(watchlo, MIPS_COP_0_WATCH_LO);
 MIPS_RW32_COP0_SEL(watchlo1, MIPS_COP_0_WATCH_LO, 1);
 MIPS_RW32_COP0_SEL(watchlo2, MIPS_COP_0_WATCH_LO, 2);
diff --git a/sys/mips/include/cpuregs.h b/sys/mips/include/cpuregs.h
index 4ce7e1b4fb2a..26bee195e648 100644
--- a/sys/mips/include/cpuregs.h
+++ b/sys/mips/include/cpuregs.h
@@ -522,12 +522,18 @@
 
 #define	MIPS_COP_0_COUNT	_(9)
 #define	MIPS_COP_0_COMPARE	_(11)
-
+#ifdef CPU_XBURST
+#define	MIPS_COP_0_XBURST_C12	_(12)
+#endif
 #define	MIPS_COP_0_CONFIG	_(16)
 #define	MIPS_COP_0_LLADDR	_(17)
 #define	MIPS_COP_0_WATCH_LO	_(18)
 #define	MIPS_COP_0_WATCH_HI	_(19)
 #define	MIPS_COP_0_TLB_XCONTEXT _(20)
+#ifdef CPU_XBURST
+#define	MIPS_COP_0_XBURST_MBOX	_(20)
+#endif
+
 #define	MIPS_COP_0_ECC		_(26)
 #define	MIPS_COP_0_CACHE_ERR	_(27)
 #define	MIPS_COP_0_TAG_LO	_(28)