Index: src/runtime/sys_openbsd2.go
--- src/runtime/sys_openbsd2.go.orig
+++ src/runtime/sys_openbsd2.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build openbsd && !mips64
+//go:build openbsd
 
 package runtime
 
@@ -40,6 +40,8 @@ func raiseproc_trampoline()
 //go:nosplit
 //go:cgo_unsafe_args
 func thrkill(tid int32, sig int) {
+	// TODO(jsing): sig should really be uint32 rather than a Go int,
+	// which switches between int32 and int64 depending on arch.
 	libcCall(unsafe.Pointer(abi.FuncPCABI0(thrkill_trampoline)), unsafe.Pointer(&tid))
 }
 func thrkill_trampoline()