diff --git a/litex/soc/cores/cpu/microwatt/boot-helper.S b/litex/soc/cores/cpu/microwatt/boot-helper.S
index 8dc226df0..bc2b0395b 100644
--- a/litex/soc/cores/cpu/microwatt/boot-helper.S
+++ b/litex/soc/cores/cpu/microwatt/boot-helper.S
@@ -1,4 +1,7 @@
 .section    .text, "ax", @progbits
 .global     boot_helper
+// void boot_helper(unsigned long r1, unsigned long r2, unsigned long r3, unsigned long addr)
 boot_helper:
-	nop # FIXME
+	mtctr 	%r6,
+	bctrl
+	ba	0