diff --git a/src/cmd/link/internal/ld/pcln.go b/src/cmd/link/internal/ld/pcln.go
index d317501d47..1ebd7de662 100644
--- a/src/cmd/link/internal/ld/pcln.go
+++ b/src/cmd/link/internal/ld/pcln.go
@@ -248,6 +248,9 @@ func (ctxt *Link) pclntab() {
 		setaddr(ctxt, ftab, 8+int64(SysArch.PtrSize)+int64(nfunc)*2*int64(SysArch.PtrSize), s)
 		setuintxx(ctxt, ftab, 8+int64(SysArch.PtrSize)+int64(nfunc)*2*int64(SysArch.PtrSize)+int64(SysArch.PtrSize), uint64(funcstart), int64(SysArch.PtrSize))
 
+		// Write runtime._func. Keep in sync with ../../../../runtime/runtime2.go:/_func
+		// and package debug/gosym.
+
 		// fixed size of struct, checked below
 		off := funcstart
 
diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index 696ea81e00..72524f53af 100644
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -615,7 +615,7 @@ const (
 
 // Layout of in-memory per-function information prepared by linker
 // See https://golang.org/s/go12symtab.
-// Keep in sync with linker
+// Keep in sync with linker (../cmd/link/internal/ld/pcln.go:/pclntab)
 // and with package debug/gosym and with symtab.go in package runtime.
 type _func struct {
 	entry   uintptr // start pc