diff --git a/src/cmd/gc/swt.c b/src/cmd/gc/swt.c
index e1d8af8786..ca5455d479 100644
--- a/src/cmd/gc/swt.c
+++ b/src/cmd/gc/swt.c
@@ -939,6 +939,8 @@ typecheckswitch(Node *n)
 					// multiple entry type switch or default
 					nvar->ntype = typenod(n->type);
 				}
+				typecheck(&nvar, Erv | Easgn);
+				ncase->nname = nvar;
 			}
 		}
 		typechecklist(ncase->nbody, Etop);
diff --git a/test/fixedbugs/issue9731.go b/test/fixedbugs/issue9731.go
new file mode 100644
index 0000000000..286cebd7b6
--- /dev/null
+++ b/test/fixedbugs/issue9731.go
@@ -0,0 +1,21 @@
+// compile
+
+// Copyright 2014 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 p
+
+func f(x interface{}) {
+	switch x := x.(type) {
+	case int:
+		func() {
+			_ = x
+		}()
+	case map[int]int:
+		func() {
+			for range x {
+			}
+		}()
+	}
+}