diff --git a/packer/rpc/builder.go b/packer/rpc/builder.go
index b6b46acb5..1c35e7ed7 100644
--- a/packer/rpc/builder.go
+++ b/packer/rpc/builder.go
@@ -93,7 +93,9 @@ func (b *builder) Run(ui packer.Ui, hook packer.Hook) packer.Artifact {
 }
 
 func (b *builder) Cancel() {
-
+	if err := b.client.Call("Builder.Cancel", new(interface{}), new(interface{})); err != nil {
+		panic(err)
+	}
 }
 
 func (b *BuilderServer) Prepare(args *BuilderPrepareArgs, reply *error) error {
@@ -135,3 +137,8 @@ func (b *BuilderServer) Run(args *BuilderRunArgs, reply *interface{}) error {
 
 	return nil
 }
+
+func (b *BuilderServer) Cancel(args *interface{}, reply*interface{}) error {
+	b.builder.Cancel()
+	return nil
+}
diff --git a/packer/rpc/builder_test.go b/packer/rpc/builder_test.go
index 790161acf..a17f0c229 100644
--- a/packer/rpc/builder_test.go
+++ b/packer/rpc/builder_test.go
@@ -73,6 +73,10 @@ func TestBuilderRPC(t *testing.T) {
 
 		assert.Equal(artifact.Id(), testBuilderArtifact.Id(), "should have artifact Id")
 	}
+
+	// Test Cancel
+	bClient.Cancel()
+	assert.True(b.cancelCalled, "cancel should be called")
 }
 
 func TestBuilder_ImplementsBuilder(t *testing.T) {
diff --git a/packer/rpc/server.go b/packer/rpc/server.go
index 9a1037b74..6767b858d 100644
--- a/packer/rpc/server.go
+++ b/packer/rpc/server.go
@@ -66,7 +66,7 @@ func serveSingleConn(s *rpc.Server) string {
 		defer l.Close()
 		conn, err := l.Accept()
 		if err != nil {
-			return
+			panic(err)
 		}
 
 		s.ServeConn(conn)