diff --git a/rpcserver.go b/rpcserver.go
index 4f808c012..eba7e0474 100644
--- a/rpcserver.go
+++ b/rpcserver.go
@@ -65,6 +65,11 @@ const (
 	hash1Len = (1 + ((btcwire.HashSize + 8) / fastsha256.BlockSize)) *
 		fastsha256.BlockSize
 
+	// gbtNonceRange is two 32-bit big-endian hexadecimal integers which
+	// represent the valid ranges of nonces returned by the getblocktemplate
+	// RPC.
+	gbtNonceRange = "00000000ffffffff"
+
 	// gbtRegenerateSeconds is the number of seconds that must pass before
 	// a new template is generated when the previous block hash has not
 	// changed and there have been changes to the available transactions
@@ -73,6 +78,14 @@ const (
 )
 
 var (
+	// gbtMutableFields are the manipulations the server allows to be made
+	// to block templates generated by the getblocktemplate RPC.  It is
+	// declared here to avoid the overhead of creating the slice on every
+	// invocation for constant data.
+	gbtMutableFields = []string{
+		"time", "transactions/add", "prevblock", "coinbase/append",
+	}
+
 	// gbtCoinbaseAux describes additional data that miners should include
 	// in the coinbase signature script.  It is declared here to avoid the
 	// overhead of creating a new object on every invocation for constant
@@ -1547,11 +1560,36 @@ func (state *gbtWorkState) updateBlockTemplate(s *rpcServer, useCoinbaseValue bo
 //
 // This function MUST be called with the state locked.
 func (state *gbtWorkState) blockTemplateResult(useCoinbaseValue bool, submitOld *bool) (*btcjson.GetBlockTemplateResult, error) {
+	// Ensure the timestamps are still in valid range for the template.
+	// This should really only ever happen if the local clock is changed
+	// after the template is generated, but it's important to avoid serving
+	// invalid block templates.
+	template := state.template
+	msgBlock := template.block
+	header := &msgBlock.Header
+	curTime := time.Now()
+	if curTime.Before(state.minTimestamp) {
+		return nil, btcjson.Error{
+			Code: btcjson.ErrOutOfRange.Code,
+			Message: fmt.Sprintf("The local time is before the "+
+				"minimum allowed time for a block - current "+
+				"time %v, minimum time %v", curTime,
+				state.minTimestamp),
+		}
+	}
+	maxTime := curTime.Add(time.Second * btcchain.MaxTimeOffsetSeconds)
+	if header.Timestamp.After(maxTime) {
+		return nil, btcjson.Error{
+			Code: btcjson.ErrOutOfRange.Code,
+			Message: fmt.Sprintf("The template time is after the "+
+				"maximum allowed time for a block - template "+
+				"time %v, maximum time %v", curTime, maxTime),
+		}
+	}
+
 	// Convert each transaction in the block template to a template result
 	// transaction.  The result does not include the coinbase, so notice
 	// the adjustments to the various lengths and indices.
-	template := state.template
-	msgBlock := template.block
 	numTx := len(msgBlock.Transactions)
 	transactions := make([]btcjson.GetBlockTemplateResultTx, 0, numTx-1)
 	txIndex := make(map[btcwire.ShaHash]int64, numTx)
@@ -1600,13 +1638,15 @@ func (state *gbtWorkState) blockTemplateResult(useCoinbaseValue bool, submitOld
 		transactions = append(transactions, resultTx)
 	}
 
-	// Generate the block template reply.
-	header := &msgBlock.Header
+	// Generate the block template reply.  Note that following mutations are
+	// implied by the included or omission of fields:
+	//  Including MinTime -> time/decrement
+	//  Omitting CoinbaseTxn -> coinbase, generation
 	targetDifficulty := fmt.Sprintf("%064x", btcchain.CompactToBig(header.Bits))
 	templateID := encodeTemplateID(state.prevHash, state.lastGenerated)
 	reply := btcjson.GetBlockTemplateResult{
 		Bits:         strconv.FormatInt(int64(header.Bits), 16),
-		CurTime:      time.Now().Unix(),
+		CurTime:      curTime.Unix(),
 		Height:       template.height,
 		PreviousHash: header.PrevBlock.String(),
 		SigOpLimit:   btcchain.MaxSigOpsPerBlock,
@@ -1616,6 +1656,10 @@ func (state *gbtWorkState) blockTemplateResult(useCoinbaseValue bool, submitOld
 		LongPollID:   templateID,
 		SubmitOld:    submitOld,
 		Target:       targetDifficulty,
+		MinTime:      state.minTimestamp.Unix(),
+		MaxTime:      maxTime.Unix(),
+		Mutable:      gbtMutableFields,
+		NonceRange:   gbtNonceRange,
 		Capabilities: gbtCapabilities,
 	}
 	if useCoinbaseValue {