diff --git a/src/core/piobject.cpp b/src/core/piobject.cpp
index c93bad88..3326ce9f 100755
--- a/src/core/piobject.cpp
+++ b/src/core/piobject.cpp
@@ -95,6 +95,7 @@ void PIObject::piConnect(const PIString & src, const PIString & sig, void * dest
 		return;
 	}
 	PIMutexLocker _ml(o->mutex_connect);
+	PIMutexLocker _mld(((PIObject*)dest)->mutex_connect, ((PIObject*)dest) != o);
 	o->connections << Connection(ev_h, 0, sig, (PIObject*)dest, dest);
 	((PIObject*)dest)->connectors << o;
 }
@@ -106,7 +107,8 @@ void PIObject::piConnect(PIObject * src, const PIString & sig, const PIString &
 		piCout << "[PIObject] Can`t find object with name \"" << dest << "\"!";
 		return;
 	}
-	PIMutexLocker _ml(o->mutex_connect);
+	PIMutexLocker _ml(src->mutex_connect);
+	PIMutexLocker _mld(o->mutex_connect, src != o);
 	src->connections << Connection(ev_h, 0, sig, o, o);
 	((PIObject*)o)->connectors << src;
 }
@@ -124,6 +126,7 @@ void PIObject::piConnect(const PIString & src, const PIString & sig, const PIStr
 		return;
 	}
 	PIMutexLocker _ml(s->mutex_connect);
+	PIMutexLocker _mld(d->mutex_connect, s != d);
 	s->connections << Connection(ev_h, 0, sig, d, d);
 	d->connectors << s;
 }
@@ -203,6 +206,7 @@ void PIObject::piConnect(PIObject * src, const PIString & sig, PIObject * dest_o
 	//piCout << "piConnect" << src << (void*)(dest) << sig;
 	//piCout << "piConnect" << src->className() << "->" << ((PIObject*)dest)->className();
 	PIMutexLocker _ml(src->mutex_connect);
+	PIMutexLocker _mld(dest_o->mutex_connect, src != dest_o);
 	src->connections << Connection(ev_h, e_h, sig, dest_o, dest, args);
 	//piCout << "piConnect" << ((PIObject*)dest) << sig << ((PIObject*)dest)->connectors.size_s() << "...";
 	//piCout << "addConnector" << dest_o << src;
@@ -214,7 +218,17 @@ void PIObject::piConnect(PIObject * src, const PIString & sig, PIObject * dest_o
 
 bool PIObject::piConnectU(PIObject * src, const PIString & ename, PIObject * dest_o, void * dest, const PIString & hname) {
 	if (src == 0 || dest_o == 0 || dest == 0) return false;
+	if (!src->isPIObject()) {
+		piCout << "[piConnectU] \"" << ename << "\" -> \"" << hname << "\" error: source object is not PIObject!";
+		return false;
+	}
+	if (!dest_o->isPIObject()) {
+		piCout << "[piConnectU] \"" << ename << "\" -> \"" << hname << "\" error: destination object is not PIObject!";
+		return false;
+	}
 	PIMutexLocker ml(__eh_mutex);
+	PIMutexLocker mls(src->mutex_connect);
+	PIMutexLocker mld(dest_o->mutex_connect, src != dest_o);
 	PIVector<__EHFunc> m_src = src->findEH(ename), m_dest = dest_o->findEH(hname);
 	if (m_src.isEmpty()) {
 		piCout << "[piConnectU] Error: can`t find event \"" << ename << "\" in class \"" << src->className() << "\"!";
@@ -251,6 +265,7 @@ bool PIObject::piConnectU(PIObject * src, const PIString & ename, PIObject * des
 
 void PIObject::piDisconnect(PIObject * src, const PIString & sig, PIObject * dest, void * ev_h) {
 	PIMutexLocker _ml(src->mutex_connect);
+	PIMutexLocker _mld(dest->mutex_connect, src != dest);
 	for (int i = 0; i < src->connections.size_s(); ++i) {
 		Connection & cc(src->connections[i]);
 		if (cc.event == sig && cc.dest_o == dest && cc.slot == ev_h) {
@@ -264,6 +279,7 @@ void PIObject::piDisconnect(PIObject * src, const PIString & sig, PIObject * des
 
 void PIObject::piDisconnect(PIObject * src, const PIString & sig, PIObject * dest) {
 	PIMutexLocker _ml(src->mutex_connect);
+	PIMutexLocker _mld(dest->mutex_connect, src != dest);
 	for (int i = 0; i < src->connections.size_s(); ++i) {
 		Connection & cc(src->connections[i]);
 		if (cc.event == sig && cc.dest_o == dest) {
@@ -283,6 +299,7 @@ void PIObject::piDisconnect(PIObject * src, const PIString & sig) {
 			PIObject * dest = cc.dest_o;
 			src->connections.remove(i);
 			i--;
+			PIMutexLocker _mld(dest->mutex_connect, src != dest);
 			dest->updateConnectors();
 		}
 	}
@@ -295,6 +312,7 @@ void PIObject::piDisconnect(PIObject * src) {
 	PIVector<PIObject * > cv = src->connectors.toVector();
 	piForeach (PIObject * o, cv) {
 		if (o == src) continue;
+		PIMutexLocker _mld(o->mutex_connect, src != o);
 		PIVector<Connection> & oc(o->connections);
 		for (int i = 0; i < oc.size_s(); ++i) {
 			//piCout << "    check" << (void*)(oc[i].dest_o) << "==" << (void*)(src);
diff --git a/src/thread/pimutex.h b/src/thread/pimutex.h
index bd2d09f6..8827c793 100755
--- a/src/thread/pimutex.h
+++ b/src/thread/pimutex.h
@@ -67,11 +67,12 @@ private:
 class PIP_EXPORT PIMutexLocker
 {
 public:
-	PIMutexLocker(PIMutex * m): mutex(m) {mutex->lock();}
-	PIMutexLocker(PIMutex & m): mutex(&m) {mutex->lock();}
-	~PIMutexLocker() {mutex->unlock();}
+	PIMutexLocker(PIMutex * m, bool condition = true): mutex(m), cond(condition) {if (cond) mutex->lock();}
+	PIMutexLocker(PIMutex & m, bool condition = true): mutex(&m), cond(condition) {if (cond) mutex->lock();}
+	~PIMutexLocker() {if (cond) mutex->unlock();}
 private:
 	PIMutex * mutex;
+	bool cond;
 };
 
 #endif // PIMUTEX_H