diff --git a/stix/kernel/Process.st b/stix/kernel/Process.st
index 5bd34a5..9092dce 100644
--- a/stix/kernel/Process.st
+++ b/stix/kernel/Process.st
@@ -68,6 +68,14 @@
 {
 	#dcl count waiting_head waiting_tail heapIndex fireTimeSec fireTimeNsec.
 
+	#method(#class) forMutualExclusion
+	{
+		| sem |
+		sem := self new.
+		sem signal.
+		^sem
+	}
+
 	#method initialize
 	{
 		self.count := 0.
@@ -104,11 +112,8 @@
 
 	#method critical: aBlock
 	{
-## TODO: implement this
-"
 		self wait.
 		^aBlock ensure: [ self signal ]
-"
 	}
 
 	## ==================================================================
diff --git a/stix/kernel/test-010.st b/stix/kernel/test-010.st
index f79d1e1..03d69f1 100644
--- a/stix/kernel/test-010.st
+++ b/stix/kernel/test-010.st
@@ -48,26 +48,25 @@
 	
 	#method(#class) main
 	{
-
-	## THIS CRASHES VM. PLEASE CHECK. CRASHES WHEN REPETITION IS 1000
 		|t1 t2 s1 s2 s3|
 
 		'START OF MAIN' dump.
 
 		s1 := Semaphore new.
-		s2 := Semaphore new.
+		s2 := Semaphore forMutualExclusion.
 
 		t1 := [ 
-			100 timesRepeat: ['BLOCK #1' dump].
-			##s2 critical: [
-			##	10 timesRepeat: ['BLOCK #1' dump ]
-			##]
+			##1000 timesRepeat: ['BLOCK #1' dump].
+			s2 critical: [
+				10000 timesRepeat: ['BLOCK #1' dump ].
+				Exception signal: 'Raised Exception at process t1'.
+			]
 		] newProcess.
 		t2 := [ 
-			100 timesRepeat: ['BLOCK #2' dump].
-			##s2 critical: [
-			##	10 timesRepeat: ['BLOCK #2' dump. ]
-			##].
+			##1000 timesRepeat: ['BLOCK #2' dump].
+			s2 critical: [
+				10000 timesRepeat: ['BLOCK #2' dump. ]
+			].
 
 			s1 signal.
 		] newProcess.