diff --git a/go.mod b/go.mod
index ac89a2d7..aac7ab6d 100644
--- a/go.mod
+++ b/go.mod
@@ -15,6 +15,7 @@ require (
 	github.com/fatih/color v1.7.0
 	github.com/go-errors/errors v1.0.1
 	github.com/gogo/protobuf v1.2.1 // indirect
+	github.com/golang-collections/collections v0.0.0-20130729185459-604e922904d3
 	github.com/google/go-cmp v0.3.0 // indirect
 	github.com/gorilla/mux v1.7.3 // indirect
 	github.com/imdario/mergo v0.3.7
diff --git a/go.sum b/go.sum
index a3486c58..398ca4c2 100644
--- a/go.sum
+++ b/go.sum
@@ -29,6 +29,8 @@ github.com/go-errors/errors v1.0.1 h1:LUHzmkK3GUKUrL/1gfBUxAHzcev3apQlezX/+O7ma6
 github.com/go-errors/errors v1.0.1/go.mod h1:f4zRHt4oKfwPJE5k8C9vpYG+aDHdBFUsgrm6/TyX73Q=
 github.com/gogo/protobuf v1.2.1 h1:/s5zKNz0uPFCZ5hddgPdo2TK2TVrUNMn0OOX8/aZMTE=
 github.com/gogo/protobuf v1.2.1/go.mod h1:hp+jE20tsWTFYpLwKvXlhS1hjn+gTNwPg2I6zVXpSg4=
+github.com/golang-collections/collections v0.0.0-20130729185459-604e922904d3 h1:zN2lZNZRflqFyxVaTIU61KNKQ9C0055u9CAfpmqUvo4=
+github.com/golang-collections/collections v0.0.0-20130729185459-604e922904d3/go.mod h1:nPpo7qLxd6XL3hWJG/O60sR8ZKfMCiIoNap5GvD12KU=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/protobuf v1.2.0 h1:P3YflyNX/ehuJFLhxviNdFxQPkGK5cDcApsge1SqnvM=