diff --git a/src/cmd/compile/internal/gc/noder.go b/src/cmd/compile/internal/gc/noder.go
index 912652110c..482578d10a 100644
--- a/src/cmd/compile/internal/gc/noder.go
+++ b/src/cmd/compile/internal/gc/noder.go
@@ -204,6 +204,9 @@ func (p *noder) varDecl(decl *syntax.VarDecl) []*Node {
 	return variter(names, typ, exprs)
 }
 
+// constState tracks state between constant specifiers within a
+// declaration group. This state is kept separate from noder so nested
+// constant declarations are handled correctly (e.g., issue 15550).
 type constState struct {
 	group  *syntax.Group
 	typ    *Node
diff --git a/test/fixedbugs/issue15550.go b/test/fixedbugs/issue15550.go
new file mode 100644
index 0000000000..f2853fc48b
--- /dev/null
+++ b/test/fixedbugs/issue15550.go
@@ -0,0 +1,28 @@
+// run
+
+// Copyright 2017 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.
+
+package main
+
+import "unsafe"
+
+const (
+	_ = unsafe.Sizeof(func() int {
+		const (
+			_ = 1
+			_
+			_
+		)
+		return 0
+	}())
+
+	y = iota
+)
+
+func main() {
+	if y != 1 {
+		panic(y)
+	}
+}