diff --git a/rpc/api.go b/rpc/api.go
index 4da2fb17a3..4a9eb59633 100644
--- a/rpc/api.go
+++ b/rpc/api.go
@@ -406,10 +406,13 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 
 		res, _ := api.xeth().DbGet([]byte(args.Database + args.Key))
 		*reply = newHexData(res)
+
 	case "shh_version":
+		// Retrieves the currently running whisper protocol version
 		*reply = api.xeth().WhisperVersion()
 
 	case "shh_post":
+		// Injects a new message into the whisper network
 		args := new(WhisperMessageArgs)
 		if err := json.Unmarshal(req.Params, &args); err != nil {
 			return err
@@ -421,18 +424,17 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 		*reply = true
 
 	case "shh_newIdentity":
+		// Creates a new whisper identity to use for sending/receiving messages
 		*reply = api.xeth().Whisper().NewIdentity()
 
 	case "shh_hasIdentity":
+		// Checks if an identity if owned or not
 		args := new(WhisperIdentityArgs)
 		if err := json.Unmarshal(req.Params, &args); err != nil {
 			return err
 		}
 		*reply = api.xeth().Whisper().HasIdentity(args.Identity)
 
-	case "shh_newGroup", "shh_addToGroup":
-		return NewNotImplementedError(req.Method)
-
 	case "shh_newFilter":
 		// Create a new filter to watch and match messages with
 		args := new(WhisperFilterArgs)
@@ -443,6 +445,7 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 		*reply = newHexNum(big.NewInt(int64(id)).Bytes())
 
 	case "shh_uninstallFilter":
+		// Remove an existing filter watching messages
 		args := new(FilterIdArgs)
 		if err := json.Unmarshal(req.Params, &args); err != nil {
 			return err
@@ -455,7 +458,7 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 		if err := json.Unmarshal(req.Params, &args); err != nil {
 			return err
 		}
-		*reply = api.xeth().MessagesChanged(args.Id)
+		*reply = api.xeth().WhisperMessagesChanged(args.Id)
 
 	case "shh_getMessages":
 		// Retrieve all the cached messages matching a specific, existing filter
@@ -463,7 +466,7 @@ func (api *EthereumApi) GetRequestReply(req *RpcRequest, reply *interface{}) err
 		if err := json.Unmarshal(req.Params, &args); err != nil {
 			return err
 		}
-		*reply = api.xeth().Messages(args.Id)
+		*reply = api.xeth().WhisperMessages(args.Id)
 
 	// case "eth_register":
 	// 	// Placeholder for actual type
diff --git a/xeth/xeth.go b/xeth/xeth.go
index ea6ae9950a..e4040d9d80 100644
--- a/xeth/xeth.go
+++ b/xeth/xeth.go
@@ -452,44 +452,60 @@ func (self *XEth) AllLogs(earliest, latest int64, skip, max int, address []strin
 	return filter.Find()
 }
 
+// NewWhisperFilter creates and registers a new message filter to watch for
+// inbound whisper messages. All parameters at this point are assumed to be
+// HEX encoded.
 func (p *XEth) NewWhisperFilter(to, from string, topics [][]string) int {
+	// Pre-define the id to be filled later
 	var id int
-	callback := func(msg WhisperMessage) {
-		p.messagesMut.Lock()
-		defer p.messagesMut.Unlock()
 
+	// Callback to delegate core whisper messages to this xeth filter
+	callback := func(msg WhisperMessage) {
+		p.messagesMut.RLock() // Only read lock to the filter pool
+		defer p.messagesMut.RUnlock()
 		p.messages[id].insert(msg)
 	}
+	// Initialize the core whisper filter and wrap into xeth
 	id = p.Whisper().Watch(to, from, topics, callback)
+
+	p.messagesMut.Lock()
 	p.messages[id] = newWhisperFilter(id, p.Whisper())
+	p.messagesMut.Unlock()
+
 	return id
 }
 
+// UninstallWhisperFilter disables and removes an existing filter.
 func (p *XEth) UninstallWhisperFilter(id int) bool {
+	p.messagesMut.Lock()
+	defer p.messagesMut.Unlock()
+
 	if _, ok := p.messages[id]; ok {
 		delete(p.messages, id)
 		return true
 	}
-
 	return false
 }
 
-func (self *XEth) MessagesChanged(id int) []WhisperMessage {
-	self.messagesMut.Lock()
-	defer self.messagesMut.Unlock()
+// WhisperMessages retrieves all the known messages that match a specific filter.
+func (self *XEth) WhisperMessages(id int) []WhisperMessage {
+	self.messagesMut.RLock()
+	defer self.messagesMut.RUnlock()
 
 	if self.messages[id] != nil {
-		return self.messages[id].retrieve()
+		return self.messages[id].messages()
 	}
 	return nil
 }
 
-func (self *XEth) Messages(id int) []WhisperMessage {
-	self.messagesMut.Lock()
-	defer self.messagesMut.Unlock()
+// WhisperMessagesChanged retrieves all the new messages matched by a filter
+// since the last retrieval
+func (self *XEth) WhisperMessagesChanged(id int) []WhisperMessage {
+	self.messagesMut.RLock()
+	defer self.messagesMut.RUnlock()
 
 	if self.messages[id] != nil {
-		return self.messages[id].messages()
+		return self.messages[id].retrieve()
 	}
 	return nil
 }