diff --git a/context.go b/context.go
index 21ad0c2..82aecc2 100644
--- a/context.go
+++ b/context.go
@@ -17,6 +17,7 @@ type ExtensionInfo struct {
 // Information about a loaded node type
 type NodeInfo struct {
   Type NodeType
+  Extensions []ExtType
 }
 
 // A Context is all the data needed to run a graphvent
@@ -39,15 +40,31 @@ func (ctx *Context) ExtByType(ext_type ExtType) ExtensionInfo {
   return ext
 }
 
-func (ctx *Context) RegisterNodeType(node_type NodeType) error {
+func (ctx *Context) RegisterNodeType(node_type NodeType, extensions []ExtType) error {
   type_hash := node_type.Hash()
   _, exists := ctx.Types[type_hash]
   if exists == true {
     return fmt.Errorf("Cannot register node type %s, type already exists in context", node_type)
   }
 
+  ext_found := map[ExtType]bool{}
+  for _, extension := range(extensions) {
+    _, in_ctx := ctx.Extensions[extension.Hash()]
+    if in_ctx == false {
+      return fmt.Errorf("Cannot register node type %s, required extension %s not in context", node_type, extension)
+    }
+
+    _, duplicate := ext_found[extension]
+    if duplicate == true {
+      return fmt.Errorf("Duplicate extension %s found in extension list", extension)
+    }
+
+    ext_found[extension] = true
+  }
+
   ctx.Types[type_hash] = NodeInfo{
     Type: node_type,
+    Extensions: extensions,
   }
   return nil
 }
diff --git a/node.go b/node.go
index 21a58bc..c1e1a58 100644
--- a/node.go
+++ b/node.go
@@ -75,13 +75,13 @@ type Node struct {
   ID NodeID
   Type NodeType
   Lock sync.RWMutex
-  ExtensionMap map[ExtType]Extension
+  Extensions map[ExtType]Extension
 }
 
 func GetExt[T Extension](node *Node) (T, error) {
   var zero T
   ext_type := zero.Type()
-  ext, exists := node.ExtensionMap[ext_type]
+  ext, exists := node.Extensions[ext_type]
   if exists == false {
     return zero, fmt.Errorf("%s does not have %s extension", node.ID, ext_type)
   }
@@ -95,17 +95,18 @@ func GetExt[T Extension](node *Node) (T, error) {
 }
 
 func (node *Node) Serialize() ([]byte, error) {
-  extensions := make([]ExtensionDB, len(node.ExtensionMap))
+  extensions := make([]ExtensionDB, len(node.Extensions))
   node_db := NodeDB{
     Header: NodeDBHeader{
       Magic: NODE_DB_MAGIC,
+      TypeHash: node.Type.Hash(),
       NumExtensions: uint32(len(extensions)),
     },
     Extensions: extensions,
   }
 
   i := 0
-  for ext_type, info := range(node.ExtensionMap) {
+  for ext_type, info := range(node.Extensions) {
     ser, err := info.Serialize()
     if err != nil {
       return nil, err
@@ -127,7 +128,7 @@ func NewNode(id NodeID, node_type NodeType) Node {
   return Node{
     ID: id,
     Type: node_type,
-    ExtensionMap: map[ExtType]Extension{},
+    Extensions: map[ExtType]Extension{},
   }
 }
 
@@ -137,14 +138,18 @@ func Allowed(context *StateContext, principal *Node, action string, node *Node)
     return fmt.Errorf("nil is not allowed to perform any actions")
   }
 
-  ext, exists := node.ExtensionMap[ACLExtType]
-  if exists == false {
-    return fmt.Errorf("%s does not have ACL extension, other nodes cannot perform actions on it", node.ID)
+  // Nodes are allowed to perform all actions on themselves regardless of whether or not they have an ACL extension
+  if principal.ID == node.ID {
+    return nil
+  }
+
+  acl_ext, err := GetExt[*ACLExt](node)
+  if err != nil {
+    return err
   }
-  acl_ext := ext.(ACLExt)
 
   for _, policy_node := range(acl_ext.Delegations) {
-    ext, exists := policy_node.ExtensionMap[ACLPolicyExtType]
+    ext, exists := policy_node.Extensions[ACLPolicyExtType]
     if exists == false {
       context.Graph.Log.Logf("policy", "WARNING: %s has dependency %s which doesn't have ACLPolicyExt")
       continue
@@ -168,7 +173,7 @@ func Signal(context *StateContext, node *Node, princ *Node, signal GraphSignal)
     return Allowed(context, princ, fmt.Sprintf("signal.%s", signal.Type()), node)
   })
 
-  for _, ext := range(node.ExtensionMap) {
+  for _, ext := range(node.Extensions) {
     err = ext.Process(context, node, signal)
     if err != nil {
       return nil
@@ -379,7 +384,7 @@ func LoadNode(ctx * Context, id NodeID) (*Node, error) {
     if err != nil {
       return nil, err
     }
-    node.ExtensionMap[def.Type] = extension
+    node.Extensions[def.Type] = extension
     ctx.Log.Logf("db", "DB_EXTENSION_LOADED: %s - 0x%x", id, type_hash)
   }
 
diff --git a/node_test.go b/node_test.go
new file mode 100644
index 0000000..71e7e8e
--- /dev/null
+++ b/node_test.go
@@ -0,0 +1,29 @@
+package graphvent
+
+import (
+  "testing"
+)
+
+func TestNodeDB(t *testing.T) {
+  ctx := logTestContext(t, []string{"test", "db", "node", "policy"})
+  node_type := NodeType("test")
+  err := ctx.RegisterNodeType(node_type, []ExtType{})
+  fatalErr(t, err)
+  node := NewNode(RandID(), node_type)
+  node.Extensions[ACLExtType] = &ACLExt{
+    Delegations: NodeMap{},
+  }
+  ctx.Nodes[node.ID] = &node
+
+  context := NewWriteContext(ctx)
+  err = UpdateStates(context, &node, NewACLInfo(&node, []string{"test"}), func(context *StateContext) error {
+    ser, err := node.Serialize()
+    ctx.Log.Logf("test", "NODE_SER: %s", ser)
+    return err
+  })
+  fatalErr(t, err)
+
+  delete(ctx.Nodes, node.ID)
+  _, err = LoadNode(ctx, node.ID)
+  fatalErr(t, err)
+}
diff --git a/policy.go b/policy.go
index 54aa110..9de62c0 100644
--- a/policy.go
+++ b/policy.go
@@ -41,7 +41,7 @@ type ACLExt struct {
   Delegations NodeMap
 }
 
-func (ext ACLExt) Process(context *StateContext, node *Node, signal GraphSignal) error {
+func (ext *ACLExt) Process(context *StateContext, node *Node, signal GraphSignal) error {
   return nil
 }
 
@@ -60,12 +60,12 @@ func LoadACLExt(ctx *Context, data []byte) (Extension, error) {
     return nil, err
   }
 
-  return ACLExt{
+  return &ACLExt{
     Delegations: delegations,
   }, nil
 }
 
-func (ext ACLExt) Serialize() ([]byte, error) {
+func (ext *ACLExt) Serialize() ([]byte, error) {
   delegations := make([]string, len(ext.Delegations))
   i := 0
   for id, _ := range(ext.Delegations) {
@@ -81,7 +81,7 @@ func (ext ACLExt) Serialize() ([]byte, error) {
 }
 
 const ACLExtType = ExtType("ACL")
-func (extension ACLExt) Type() ExtType {
+func (ext *ACLExt) Type() ExtType {
   return ACLExtType
 }