diff --git a/uppsrc/Core/Mt.cpp b/uppsrc/Core/Mt.cpp
index b84d243e5..0ca483cea 100644
--- a/uppsrc/Core/Mt.cpp
+++ b/uppsrc/Core/Mt.cpp
@@ -227,7 +227,7 @@ int Thread::Wait()
 	return out;
 }
 
-void Thread::Priority(int percent)
+bool Thread::Priority(int percent)
 {
 	ASSERT(IsOpen());
 #ifdef PLATFORM_WIN32
@@ -242,10 +242,80 @@ void Thread::Priority(int percent)
 		prior = THREAD_PRIORITY_ABOVE_NORMAL;
 	else
 		prior = THREAD_PRIORITY_HIGHEST;
-	SetThreadPriority(handle, prior);
+	return SetThreadPriority(handle, prior);
 #endif
 #ifdef PLATFORM_POSIX
-	// ToDo
+	int policy;
+	struct sched_param param;
+	
+	if(pthread_getschedparam(handle, &policy, &param))
+		return false;
+	int percen_min, percen_max;
+	if(percent <= 25) {
+		#if defined(SCHED_IDLE)
+			policy = SCHED_IDLE;
+			percen_min = 0;
+			percen_max = 25;
+		#elif defined(SCHED_BATCH)
+			policy = SCHED_BATCH;
+			percen_min = 0;
+			percen_max = 75;
+		#else
+			policy = SCHED_OTHER;
+			percen_min = 0;
+			percen_max = 125;
+		#endif
+	}
+	else
+	if(percent <= 75){
+		#if defined(SCHED_IDLE)
+			policy = SCHED_BATCH;
+			percen_min = 25;
+			percen_max = 75;
+		#elif defined(SCHED_BATCH)
+			policy = SCHED_BATCH;
+			percen_min = 0;
+			percen_max = 75;
+		#else
+			policy = SCHED_OTHER;
+			percen_min = 0;
+			percen_max = 125;
+		#endif
+	}
+	else
+	if(percent <= 125){
+		policy = SCHED_OTHER;
+		#if defined(SCHED_IDLE)
+			percen_min = 75;
+			percen_max = 125;
+		#elif defined(SCHED_BATCH)
+			percen_min = 25;
+			percen_max = 125;
+		#else
+			percen_min = 0;
+			percen_max = 125;
+		#endif
+	}
+	else
+	if(percent <= 175){ // should be the root
+		policy = SCHED_FIFO;
+		percen_min = 125;
+		percen_max = 175;
+	}
+	else
+		policy = SCHED_RR;
+	param.sched_priority = (sched_get_priority_max(policy) - sched_get_priority_min(policy))*(minmax(percent, percen_min, percen_max)-percen_min)/(percen_max - percen_min);
+	
+	if (pthread_setschedparam(handle, policy, &param)) {
+		// No privileges? Try maximum possible! Do not use EPERM as not all os support this one
+		policy = SCHED_OTHER;
+		percen_max = 125;
+		percen_min = minmax(percen_min, 0, percen_max);
+		param.sched_priority = (sched_get_priority_max(policy) - sched_get_priority_min(policy))*(minmax(percent, percen_min, percen_max)-percen_min)/(percen_max - percen_min);
+		if (pthread_setschedparam(handle, policy, &param))
+			return false;
+	}
+	return true;
 #endif
 }
 
diff --git a/uppsrc/Core/Mt.h b/uppsrc/Core/Mt.h
index c35f16b6e..6ce2d8284 100644
--- a/uppsrc/Core/Mt.h
+++ b/uppsrc/Core/Mt.h
@@ -76,7 +76,7 @@ public:
 
 	Handle      GetHandle() const              { return handle; }
 	
-	void        Priority(int percent); // 0 = lowest, 100 = normal
+	bool        Priority(int percent); // 0 = lowest, 100 = normal
 
 	static void Start(Callback cb);
 
diff --git a/uppsrc/Core/src.tpp/Thread$en-us.tpp b/uppsrc/Core/src.tpp/Thread$en-us.tpp
index 6f29d5dbe..9e9b596b9 100644
--- a/uppsrc/Core/src.tpp/Thread$en-us.tpp
+++ b/uppsrc/Core/src.tpp/Thread$en-us.tpp
@@ -97,11 +97,11 @@ client code should call the already installed function (return
 value is not null)&]
 [s3; &]
 [s4; &]
-[s5;:Thread`:`:Priority`(int`): [@(0.0.255) void]_[* Priority]([@(0.0.255) int]_[*@3 percent])
+[s5;:Thread`:`:Priority`(int`): [@(0.0.255) bool]_[* Priority]([@(0.0.255) int]_[*@3 percent])
 &]
 [s2;%% Sets the treads priority to [%-*@3 percent ][%- (0 to 200)]. In 
 reality, current implementation supports only 5 levels, 25%, 
 75%, 125%, 175% and more than 175%; last two levels require root 
-priviledges.&]
+priviledges. Returns true if setting the priority was successfull.&]
 [s3;%% &]
 [s0; ]
\ No newline at end of file