diff --git a/pkg/apimachinery/types.go b/pkg/apimachinery/types.go
index 0e90cbbe321..d42323651ac 100644
--- a/pkg/apimachinery/types.go
+++ b/pkg/apimachinery/types.go
@@ -17,6 +17,8 @@ limitations under the License.
 package apimachinery
 
 import (
+	"fmt"
+
 	"k8s.io/kubernetes/pkg/api/meta"
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/runtime"
@@ -47,6 +49,36 @@ type GroupMeta struct {
 	RESTMapper meta.RESTMapper
 
 	// InterfacesFor returns the default Codec and ResourceVersioner for a given version
-	// or an error if the version is not known.
+	// string, or an error if the version is not known.
+	// TODO: make this stop being a func pointer and always use the default
+	// function provided below once every place that populates this field has been changed.
 	InterfacesFor func(version unversioned.GroupVersion) (*meta.VersionInterfaces, error)
+
+	// InterfacesByVersion stores the per-version interfaces.
+	InterfacesByVersion map[unversioned.GroupVersion]*meta.VersionInterfaces
+}
+
+// InterfacesFor returns the default Codec and ResourceVersioner for a given version
+// string, or an error if the version is not known.
+// TODO: Remove the "Default" prefix.
+func (gm *GroupMeta) DefaultInterfacesFor(version unversioned.GroupVersion) (*meta.VersionInterfaces, error) {
+	if v, ok := gm.InterfacesByVersion[version]; ok {
+		return v, nil
+	}
+	return nil, fmt.Errorf("unsupported storage version: %s (valid: %v)", version, gm.GroupVersions)
+}
+
+// Adds the given version to the group. Only call during init, after that
+// GroupMeta objects should be immutable. Not thread safe.
+// (If you use this, be sure to set .InterfacesFor = .DefaultInterfacesFor)
+func (gm *GroupMeta) AddVersion(version unversioned.GroupVersion, interfaces *meta.VersionInterfaces) error {
+	if e, a := gm.GroupVersion.Group, version.Group; a != e {
+		return fmt.Errorf("got a version in group %v, but am in group %v", a, e)
+	}
+	if gm.InterfacesByVersion == nil {
+		gm.InterfacesByVersion = make(map[unversioned.GroupVersion]*meta.VersionInterfaces)
+	}
+	gm.InterfacesByVersion[version] = interfaces
+	gm.GroupVersions = append(gm.GroupVersions, version)
+	return nil
 }
diff --git a/pkg/apimachinery/types_test.go b/pkg/apimachinery/types_test.go
new file mode 100644
index 00000000000..7cf0e918abe
--- /dev/null
+++ b/pkg/apimachinery/types_test.go
@@ -0,0 +1,43 @@
+/*
+Copyright 2016 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package apimachinery
+
+import (
+	"testing"
+
+	"k8s.io/kubernetes/pkg/api/unversioned"
+)
+
+func TestAdd(t *testing.T) {
+	gm := GroupMeta{
+		GroupVersion: unversioned.GroupVersion{
+			Group:   "test",
+			Version: "v1",
+		},
+		GroupVersions: []unversioned.GroupVersion{{"test", "v1"}},
+	}
+
+	gm.AddVersion(unversioned.GroupVersion{"test", "v1"}, nil)
+	if e, a := 1, len(gm.InterfacesByVersion); e != a {
+		t.Errorf("expected %v, got %v")
+	}
+
+	// GroupVersions is unchanged
+	if e, a := 1, len(gm.GroupVersions); e != a {
+		t.Errorf("expected %v, got %v", e, a)
+	}
+}