diff --git a/misc/cgo/errors/issue11097a.go b/misc/cgo/errors/issue11097a.go
new file mode 100644
index 0000000000..4508213cb4
--- /dev/null
+++ b/misc/cgo/errors/issue11097a.go
@@ -0,0 +1,15 @@
+// Copyright 2015 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
+
+/*
+//enum test { foo, bar };
+*/
+import "C"
+
+func main() {
+	var a = C.enum_test(1) // ERROR HERE
+	_ = a
+}
diff --git a/misc/cgo/errors/issue11097b.go b/misc/cgo/errors/issue11097b.go
new file mode 100644
index 0000000000..68c5c7c64c
--- /dev/null
+++ b/misc/cgo/errors/issue11097b.go
@@ -0,0 +1,15 @@
+// Copyright 2015 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
+
+/*
+//enum test { foo, bar };
+*/
+import "C"
+
+func main() {
+	p := new(C.enum_test) // ERROR HERE
+	_ = p
+}
diff --git a/misc/cgo/errors/test.bash b/misc/cgo/errors/test.bash
index c880ad65c2..25ab249940 100755
--- a/misc/cgo/errors/test.bash
+++ b/misc/cgo/errors/test.bash
@@ -31,6 +31,8 @@ check err2.go
 check err3.go
 check issue7757.go
 check issue8442.go
+check issue11097a.go
+check issue11097b.go
 
 rm -rf errs _obj
 exit 0
diff --git a/src/cmd/cgo/gcc.go b/src/cmd/cgo/gcc.go
index b64849a8d1..b65b6cb7a9 100644
--- a/src/cmd/cgo/gcc.go
+++ b/src/cmd/cgo/gcc.go
@@ -607,6 +607,10 @@ func (p *Package) rewriteRef(f *File) {
 			if r.Name.Kind != "func" {
 				if r.Name.Kind == "type" {
 					r.Context = "type"
+					if r.Name.Type == nil {
+						error_(r.Pos(), "invalid conversion to C.%s: undefined C type '%s'", fixGo(r.Name.Go), r.Name.C)
+						break
+					}
 					expr = r.Name.Type.Go
 					break
 				}
@@ -658,6 +662,10 @@ func (p *Package) rewriteRef(f *File) {
 				}
 			} else if r.Name.Kind == "type" {
 				// Okay - might be new(T)
+				if r.Name.Type == nil {
+					error_(r.Pos(), "expression C.%s: undefined C type '%s'", fixGo(r.Name.Go), r.Name.C)
+					break
+				}
 				expr = r.Name.Type.Go
 			} else if r.Name.Kind == "var" {
 				expr = &ast.StarExpr{Star: (*r.Expr).Pos(), X: expr}