diff --git a/stratum/api.go b/stratum/api.go
index b6216c5..13e395c 100644
--- a/stratum/api.go
+++ b/stratum/api.go
@@ -40,9 +40,9 @@ func (s *StratumServer) StatsIndex(w http.ResponseWriter, r *http.Request) {
 
 	if t := s.currentBlockTemplate(); t != nil {
 		stats["height"] = t.height
-		stats["diff"] = t.difficulty
+		stats["diff"] = t.diffInt64
 		roundShares := atomic.LoadInt64(&s.roundShares)
-		stats["variance"] = float64(roundShares) / float64(t.difficulty)
+		stats["variance"] = float64(roundShares) / float64(t.diffInt64)
 		stats["prevHash"] = t.prevHash[0:8]
 		stats["template"] = true
 	}
diff --git a/stratum/blocks.go b/stratum/blocks.go
index 37d592d..9222b34 100644
--- a/stratum/blocks.go
+++ b/stratum/blocks.go
@@ -5,12 +5,14 @@ import (
 	"encoding/binary"
 	"encoding/hex"
 	"log"
+	"math/big"
 
 	"github.com/sammy007/monero-stratum/cnutil"
 )
 
 type BlockTemplate struct {
-	difficulty     int64
+	difficulty     *big.Int
+	diffInt64      int64
 	height         int64
 	reservedOffset int
 	prevHash       string
@@ -49,7 +51,8 @@ func (s *StratumServer) fetchBlockTemplate() bool {
 		log.Printf("New block to mine on %s at height %v, diff: %v, prev_hash: %s", r.Name, reply.Height, reply.Difficulty, reply.PrevHash)
 	}
 	newTemplate := BlockTemplate{
-		difficulty:     reply.Difficulty,
+		diffInt64:      reply.Difficulty,
+		difficulty:     big.NewInt(reply.Difficulty),
 		height:         reply.Height,
 		prevHash:       reply.PrevHash,
 		reservedOffset: reply.ReservedOffset,
diff --git a/stratum/miner.go b/stratum/miner.go
index 3d25522..983687c 100644
--- a/stratum/miner.go
+++ b/stratum/miner.go
@@ -161,8 +161,13 @@ func (m *Miner) processShare(s *StratumServer, cs *Session, job *Job, t *BlockTe
 		return false
 	}
 
-	hashDiff := util.GetHashDifficulty(hashBytes).Int64() // FIXME: Will return max int64 value if overflows
-	block := hashDiff >= t.difficulty
+	hashDiff, ok := util.GetHashDifficulty(hashBytes) // FIXME: Will return max int64 value if overflows
+	if !ok {
+		log.Printf("Bad hash from miner %v@%v", m.id, cs.ip)
+		atomic.AddInt64(&m.invalidShares, 1)
+		return false
+	}
+	block := hashDiff.Cmp(t.difficulty) >= 0
 
 	if block {
 		_, err := r.SubmitBlock(hex.EncodeToString(shareBuff))
@@ -177,7 +182,7 @@ func (m *Miner) processShare(s *StratumServer, cs *Session, job *Job, t *BlockTe
 			blockFastHash := hex.EncodeToString(hashing.FastHash(convertedBlob))
 			now := util.MakeTimestamp()
 			roundShares := atomic.SwapInt64(&s.roundShares, 0)
-			ratio := float64(roundShares) / float64(t.difficulty)
+			ratio := float64(roundShares) / float64(t.diffInt64)
 			s.blocksMu.Lock()
 			s.blockStats[now] = blockEntry{height: t.height, hash: blockFastHash, variance: ratio}
 			s.blocksMu.Unlock()
@@ -189,7 +194,7 @@ func (m *Miner) processShare(s *StratumServer, cs *Session, job *Job, t *BlockTe
 			// Immediately refresh current BT and send new jobs
 			s.refreshBlockTemplate(true)
 		}
-	} else if hashDiff < cs.endpoint.config.Difficulty {
+	} else if hashDiff.Cmp(cs.endpoint.difficulty) < 0 {
 		log.Printf("Rejected low difficulty share of %v from %v@%v", hashDiff, m.id, cs.ip)
 		atomic.AddInt64(&m.invalidShares, 1)
 		return false
diff --git a/stratum/stratum.go b/stratum/stratum.go
index 670706e..b4958e9 100644
--- a/stratum/stratum.go
+++ b/stratum/stratum.go
@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"math/big"
 	"net"
 	"sync"
 	"sync/atomic"
@@ -42,6 +43,7 @@ type blockEntry struct {
 
 type Endpoint struct {
 	config      *pool.Port
+	difficulty  *big.Int
 	instanceId  []byte
 	extraNonce  uint32
 	targetHex   string
@@ -132,6 +134,7 @@ func NewEndpoint(cfg *pool.Port) *Endpoint {
 		log.Fatalf("Can't seed with random bytes: %v", err)
 	}
 	e.targetHex = util.GetTargetHex(e.config.Difficulty)
+	e.difficulty = big.NewInt(e.config.Difficulty)
 	return e
 }
 
diff --git a/util/util.go b/util/util.go
index 775264a..b4bfdc5 100644
--- a/util/util.go
+++ b/util/util.go
@@ -31,10 +31,15 @@ func GetTargetHex(diff int64) string {
 	return targetHex
 }
 
-func GetHashDifficulty(hashBytes []byte) *big.Int {
+func GetHashDifficulty(hashBytes []byte) (*big.Int, bool) {
 	diff := new(big.Int)
 	diff.SetBytes(reverse(hashBytes))
-	return diff.Div(Diff1, diff)
+
+	// Check for broken result, empty string or zero hex value
+	if diff.Cmp(new(big.Int)) == 0 {
+		return nil, false
+	}
+	return diff.Div(Diff1, diff), true
 }
 
 func ValidateAddress(addy string, poolAddy string) bool {
diff --git a/util/util_test.go b/util/util_test.go
index 07d4d45..c7cb2b4 100644
--- a/util/util_test.go
+++ b/util/util_test.go
@@ -2,7 +2,6 @@ package util
 
 import (
 	"encoding/hex"
-	"math/big"
 	"testing"
 )
 
@@ -23,11 +22,19 @@ func TestGetTargetHex(t *testing.T) {
 func TestGetHashDifficulty(t *testing.T) {
 	hash := "8e3c1865f22801dc3df0a688da80701e2390e7838e65c142604cc00eafe34000"
 	hashBytes, _ := hex.DecodeString(hash)
-	diff := new(big.Int)
-	diff.SetBytes(reverse(hashBytes))
-	shareDiff := GetHashDifficulty(hashBytes)
+	shareDiff, ok := GetHashDifficulty(hashBytes)
 
-	if shareDiff.String() != "1009" {
+	if !ok && shareDiff.String() != "1009" {
 		t.Error("Invalid diff")
 	}
 }
+
+func TestGetHashDifficultyWothBrokenHash(t *testing.T) {
+	hash := ""
+	hashBytes, _ := hex.DecodeString(hash)
+	shareDiff, ok := GetHashDifficulty(hashBytes)
+
+	if ok || shareDiff != nil {
+		t.Error("Must be no result and not ok")
+	}
+}