diff --git a/PBGitHistoryGrapher.m b/PBGitHistoryGrapher.m
index 891d342..65d2311 100644
--- a/PBGitHistoryGrapher.m
+++ b/PBGitHistoryGrapher.m
@@ -38,10 +38,13 @@
 	if (!revList || [revList count] == 0)
 		return;
 
+	NSThread *currentThread = [NSThread currentThread];
 	NSMutableArray *commits = [NSMutableArray array];
 	NSInteger counter = 0;
 
 	for (PBGitCommit *commit in revList) {
+		if ([currentThread isCancelled])
+			return;
 		PBGitSHA *commitSHA = [commit sha];
 		if (viewAllBranches || [searchSHAs containsObject:commitSHA]) {
 			[grapher decorateCommit:commit];
diff --git a/PBGitHistoryList.h b/PBGitHistoryList.h
index 9f00a66..2b07007 100644
--- a/PBGitHistoryList.h
+++ b/PBGitHistoryList.h
@@ -40,6 +40,7 @@
 - (id) initWithRepository:(PBGitRepository *)repo;
 - (void) forceUpdate;
 - (void) updateHistory;
+- (void)cleanup;
 
 - (void) updateCommitsFromGrapher:(NSDictionary *)commitData;
 
diff --git a/PBGitHistoryList.m b/PBGitHistoryList.m
index 017a757..a121ad1 100644
--- a/PBGitHistoryList.m
+++ b/PBGitHistoryList.m
@@ -82,6 +82,20 @@
 }
 
 
+- (void)cleanup
+{
+	if (currentRevList) {
+		[currentRevList removeObserver:self forKeyPath:@"commits"];
+		[currentRevList cancel];
+	}
+	[graphQueue cancelAllOperations];
+
+	[repository removeObserver:self forKeyPath:@"currentBranch"];
+	[repository removeObserver:self forKeyPath:@"currentBranchFilter"];
+	[repository removeObserver:self forKeyPath:@"hasChanged"];
+}
+
+
 - (NSArray *) projectCommits
 {
 	return [projectRevList.commits copy];
@@ -137,12 +151,9 @@
 	resetCommits = YES;
 	self.isUpdating = YES;
 
-	[graphQueue setSuspended:YES];
-	if (graphQueue)
-		[graphQueue removeObserver:self forKeyPath:@"operations"];
+	[graphQueue cancelAllOperations];
 	graphQueue = [[NSOperationQueue alloc] init];
 	[graphQueue setMaxConcurrentOperationCount:1];
-	[graphQueue addObserver:self forKeyPath:@"operations" options:0 context:@"operations"];
 
 	grapher = [self grapher];
 }
@@ -223,15 +234,12 @@
 	if (currentRevList == parser)
 		return;
 
-	if (currentRevList) {
+	if (currentRevList)
 		[currentRevList removeObserver:self forKeyPath:@"commits"];
-		[currentRevList removeObserver:self forKeyPath:@"isParsing"];
-	}
 
 	currentRevList = parser;
 
 	[currentRevList addObserver:self forKeyPath:@"commits" options:NSKeyValueObservingOptionNew context:@"commitsUpdated"];
-	[currentRevList addObserver:self forKeyPath:@"isParsing" options:0 context:@"revListParsing"];
 }
 
 
@@ -339,22 +347,6 @@
 #pragma mark -
 #pragma mark Key Value Observing
 
-- (void) removeObservers
-{
-	[repository removeObserver:self forKeyPath:@"currentBranch"];
-	[repository removeObserver:self forKeyPath:@"currentBranchFilter"];
-	[repository removeObserver:self forKeyPath:@"hasChanged"];
-
-	if (currentRevList) {
-		[currentRevList removeObserver:self forKeyPath:@"commits"];
-		[currentRevList removeObserver:self forKeyPath:@"isParsing"];
-	}
-
-	if (graphQueue)
-		[graphQueue removeObserver:self forKeyPath:@"operations"];
-}
-
-
 - (void) observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
 {
 	if ([@"currentBranch" isEqualToString:context]) {
@@ -379,11 +371,6 @@
 		return;
 	}
 
-	if ([@"revListParsing" isEqualToString:context] || [@"operations" isEqualToString:context]) {
-		[self finishedGraphing];
-		return;
-	}
-
 	[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
 }
 
diff --git a/PBGitRepository.m b/PBGitRepository.m
index f9f9175..5b77b23 100644
--- a/PBGitRepository.m
+++ b/PBGitRepository.m
@@ -128,6 +128,13 @@ NSString* PBGitRepositoryErrorDomain = @"GitXErrorDomain";
 	revisionList = [[PBGitHistoryList alloc] initWithRepository:self];
 }
 
+- (void)close
+{
+	[revisionList cleanup];
+
+	[super close];
+}
+
 - (id) initWithURL: (NSURL*) path
 {
 	if (![PBGitBinary path])
diff --git a/PBGitRevList.h b/PBGitRevList.h
index 7370711..0fe216d 100644
--- a/PBGitRevList.h
+++ b/PBGitRevList.h
@@ -25,6 +25,7 @@
 
 - (id) initWithRepository:(PBGitRepository *)repo rev:(PBGitRevSpecifier *)rev shouldGraph:(BOOL)graph;
 - (void) loadRevisons;
+- (void)cancel;
 
 @property (retain) NSMutableArray *commits;
 @property (readonly) BOOL isParsing;
diff --git a/PBGitRevList.mm b/PBGitRevList.mm
index ea0933d..00a1920 100644
--- a/PBGitRevList.mm
+++ b/PBGitRevList.mm
@@ -58,6 +58,12 @@ using namespace std;
 }
 
 
+- (void)cancel
+{
+	[parseThread cancel];
+}
+
+
 - (void) finishedParsing
 {
 	self.isParsing = NO;
@@ -217,6 +223,7 @@ using namespace std;
 		NSLog(@"[%@ %s] thread has been canceled", [self class], _cmd);
 	}
 
+	[task terminate];
 	[task waitUntilExit];
 }