diff --git a/src/pkg/runtime/funcdata.h b/src/pkg/runtime/funcdata.h
new file mode 100644
index 0000000..8fcadcb
--- /dev/null
+++ b/src/pkg/runtime/funcdata.h
@@ -0,0 +1,13 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// This file defines the IDs for PCDATA and FUNCDATA instructions
+// in Go binaries. It is included by both C and assembly, so it must
+// be written using #defines. It is included by the runtime package
+// as well as the compilers.
+
+#define PCDATA_ArgSize 0
+
+// To be used in assembly.
+#define ARGSIZE(n) PCDATA $PCDATA_ArgSize, $n