diff --git a/whisper/whisperv6/api.go b/whisper/whisperv6/api.go
index f6158b641c..3dddb69539 100644
--- a/whisper/whisperv6/api.go
+++ b/whisper/whisperv6/api.go
@@ -118,7 +118,7 @@ func (api *PublicWhisperAPI) SetMaxMessageSize(ctx context.Context, size uint32)
 
 // SetMinPow sets the minimum PoW for a message before it is accepted.
 func (api *PublicWhisperAPI) SetMinPoW(ctx context.Context, pow float64) (bool, error) {
-	return true, api.w.SetMinimumPoW(pow, false)
+	return true, api.w.SetMinimumPoW(pow)
 }
 
 // MarkTrustedPeer marks a peer trusted. , which will allow it to send historic (expired) messages.
diff --git a/whisper/whisperv6/peer_test.go b/whisper/whisperv6/peer_test.go
index 2c36fd7cb5..599a479be4 100644
--- a/whisper/whisperv6/peer_test.go
+++ b/whisper/whisperv6/peer_test.go
@@ -124,7 +124,7 @@ func initialize(t *testing.T) {
 	for i := 0; i < NumNodes; i++ {
 		var node TestNode
 		node.shh = New(&DefaultConfig)
-		node.shh.SetMinimumPoW(0.00000001, true)
+		node.shh.SetMinimumPowTest(0.00000001)
 		node.shh.Start(nil)
 		topics := make([]TopicType, 0)
 		topics = append(topics, sharedTopic)
@@ -342,7 +342,7 @@ func powReqExchange(t *testing.T) {
 	}
 
 	const pow float64 = 7777777.0
-	nodes[0].shh.SetMinimumPoW(pow, true)
+	nodes[0].shh.SetMinimumPoW(pow)
 
 	// wait until all the messages are delivered
 	time.Sleep(64 * time.Millisecond)
diff --git a/whisper/whisperv6/whisper.go b/whisper/whisperv6/whisper.go
index 57b190368d..497819ef9f 100644
--- a/whisper/whisperv6/whisper.go
+++ b/whisper/whisperv6/whisper.go
@@ -181,30 +181,40 @@ func (w *Whisper) SetMaxMessageSize(size uint32) error {
 }
 
 // SetMinimumPoW sets the minimal PoW required by this node
-func (w *Whisper) SetMinimumPoW(val float64, testMode bool) error {
-	if val <= 0.0 {
+func (w *Whisper) SetMinimumPoW(val float64) error {
+	if val < 0.0 {
 		return fmt.Errorf("invalid PoW: %f", val)
 	}
 
 	w.notifyPeersAboutPowRequirementChange(val)
 
-	if testMode {
+	go func() {
+		// allow some time before all the peers have processed the notification
+		time.Sleep(time.Duration(w.reactionAllowance) * time.Second)
 		w.settings.Store(minPowIdx, val)
-	} else {
-		go func() {
-			// allow some time before all the peers have processed the notification
-			time.Sleep(time.Duration(w.reactionAllowance) * time.Second)
-			w.settings.Store(minPowIdx, val)
-		}()
-	}
+	}()
 
 	return nil
 }
 
+// SetMinimumPoW sets the minimal PoW in test environment
+func (w *Whisper) SetMinimumPowTest(val float64) {
+	w.notifyPeersAboutPowRequirementChange(val)
+	w.settings.Store(minPowIdx, val)
+}
+
 func (w *Whisper) notifyPeersAboutPowRequirementChange(pow float64) {
+	arr := make([]*Peer, len(w.peers))
+	i := 0
+
 	w.peerMu.Lock()
-	defer w.peerMu.Unlock()
 	for p := range w.peers {
+		arr[i] = p
+		i++
+	}
+	w.peerMu.Unlock()
+
+	for _, p := range arr {
 		err := p.notifyAboutPowRequirementChange(pow)
 		if err != nil {
 			// allow one retry
diff --git a/whisper/whisperv6/whisper_test.go b/whisper/whisperv6/whisper_test.go
index 009f50d3cb..b391a1161b 100644
--- a/whisper/whisperv6/whisper_test.go
+++ b/whisper/whisperv6/whisper_test.go
@@ -472,8 +472,8 @@ func TestExpiry(t *testing.T) {
 	InitSingleTest()
 
 	w := New(&DefaultConfig)
-	w.SetMinimumPoW(0.0000001, true)
-	defer w.SetMinimumPoW(DefaultMinimumPoW, true)
+	w.SetMinimumPowTest(0.0000001)
+	defer w.SetMinimumPowTest(DefaultMinimumPoW)
 	w.Start(nil)
 	defer w.Stop()
 
@@ -529,7 +529,7 @@ func TestCustomization(t *testing.T) {
 	InitSingleTest()
 
 	w := New(&DefaultConfig)
-	defer w.SetMinimumPoW(DefaultMinimumPoW, true)
+	defer w.SetMinimumPowTest(DefaultMinimumPoW)
 	defer w.SetMaxMessageSize(DefaultMaxMessageSize)
 	w.Start(nil)
 	defer w.Stop()
@@ -563,7 +563,7 @@ func TestCustomization(t *testing.T) {
 		t.Fatalf("successfully sent envelope with PoW %.06f, false positive (seed %d).", env.PoW(), seed)
 	}
 
-	w.SetMinimumPoW(smallPoW/2, true)
+	w.SetMinimumPowTest(smallPoW / 2)
 	err = w.Send(env)
 	if err != nil {
 		t.Fatalf("failed to send envelope with seed %d: %s.", seed, err)
@@ -625,7 +625,7 @@ func TestSymmetricSendCycle(t *testing.T) {
 	InitSingleTest()
 
 	w := New(&DefaultConfig)
-	defer w.SetMinimumPoW(DefaultMinimumPoW, true)
+	defer w.SetMinimumPowTest(DefaultMinimumPoW)
 	defer w.SetMaxMessageSize(DefaultMaxMessageSize)
 	w.Start(nil)
 	defer w.Stop()
@@ -714,7 +714,7 @@ func TestSymmetricSendWithoutAKey(t *testing.T) {
 	InitSingleTest()
 
 	w := New(&DefaultConfig)
-	defer w.SetMinimumPoW(DefaultMinimumPoW, true)
+	defer w.SetMinimumPowTest(DefaultMinimumPoW)
 	defer w.SetMaxMessageSize(DefaultMaxMessageSize)
 	w.Start(nil)
 	defer w.Stop()
@@ -782,7 +782,7 @@ func TestSymmetricSendKeyMismatch(t *testing.T) {
 	InitSingleTest()
 
 	w := New(&DefaultConfig)
-	defer w.SetMinimumPoW(DefaultMinimumPoW, true)
+	defer w.SetMinimumPowTest(DefaultMinimumPoW)
 	defer w.SetMaxMessageSize(DefaultMaxMessageSize)
 	w.Start(nil)
 	defer w.Stop()