diff --git a/GitX.xcodeproj/project.pbxproj b/GitX.xcodeproj/project.pbxproj
index c0f7d62..331d554 100644
--- a/GitX.xcodeproj/project.pbxproj
+++ b/GitX.xcodeproj/project.pbxproj
@@ -73,6 +73,7 @@
 		D8E105471157C18200FC28A4 /* PBQLTextView.m in Sources */ = {isa = PBXBuildFile; fileRef = D8E105461157C18200FC28A4 /* PBQLTextView.m */; };
 		D8E3B2B810DC9FB2001096A3 /* ScriptingBridge.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = D8E3B2B710DC9FB2001096A3 /* ScriptingBridge.framework */; };
 		D8E3B34D10DCA958001096A3 /* PBCreateTagSheet.m in Sources */ = {isa = PBXBuildFile; fileRef = D8E3B34C10DCA958001096A3 /* PBCreateTagSheet.m */; };
+		D8FBCF19115FA20C0098676A /* PBGitSHA.m in Sources */ = {isa = PBXBuildFile; fileRef = D8FBCF18115FA20C0098676A /* PBGitSHA.m */; };
 		D8FDD9F711432A12005647F6 /* PBCloneRepositoryPanel.xib in Resources */ = {isa = PBXBuildFile; fileRef = D8FDD9F511432A12005647F6 /* PBCloneRepositoryPanel.xib */; };
 		D8FDDA6A114335E8005647F6 /* PBGitSVBranchItem.m in Sources */ = {isa = PBXBuildFile; fileRef = D8FDDA5D114335E8005647F6 /* PBGitSVBranchItem.m */; };
 		D8FDDA6B114335E8005647F6 /* PBGitSVFolderItem.m in Sources */ = {isa = PBXBuildFile; fileRef = D8FDDA5F114335E8005647F6 /* PBGitSVFolderItem.m */; };
@@ -293,6 +294,8 @@
 		D8E3B34B10DCA958001096A3 /* PBCreateTagSheet.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = PBCreateTagSheet.h; sourceTree = "<group>"; };
 		D8E3B34C10DCA958001096A3 /* PBCreateTagSheet.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = PBCreateTagSheet.m; sourceTree = "<group>"; };
 		D8E3B38110DD4E2C001096A3 /* English */ = {isa = PBXFileReference; lastKnownFileType = file.xib; name = English; path = English.lproj/PBCreateTagSheet.xib; sourceTree = "<group>"; };
+		D8FBCF17115FA20C0098676A /* PBGitSHA.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = PBGitSHA.h; sourceTree = "<group>"; };
+		D8FBCF18115FA20C0098676A /* PBGitSHA.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = PBGitSHA.m; sourceTree = "<group>"; };
 		D8FDD9F611432A12005647F6 /* English */ = {isa = PBXFileReference; lastKnownFileType = file.xib; name = English; path = English.lproj/PBCloneRepositoryPanel.xib; sourceTree = "<group>"; };
 		D8FDDA5C114335E8005647F6 /* PBGitSVBranchItem.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = PBGitSVBranchItem.h; sourceTree = "<group>"; };
 		D8FDDA5D114335E8005647F6 /* PBGitSVBranchItem.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = PBGitSVBranchItem.m; sourceTree = "<group>"; };
@@ -828,6 +831,8 @@
 				F56524EF0E02D45200F03B52 /* PBGitCommit.m */,
 				F5C007730E731B48007B84B2 /* PBGitRef.h */,
 				F5C007740E731B48007B84B2 /* PBGitRef.m */,
+				D8FBCF17115FA20C0098676A /* PBGitSHA.h */,
+				D8FBCF18115FA20C0098676A /* PBGitSHA.m */,
 				D8295D281130A1DC00C838E8 /* PBGitHistoryList.h */,
 				D8295D291130A1DC00C838E8 /* PBGitHistoryList.m */,
 				F5FF4E160E0829C20006317A /* PBGitRevList.h */,
@@ -1175,6 +1180,7 @@
 				D8295D2A1130A1DC00C838E8 /* PBGitHistoryList.m in Sources */,
 				D8295DE01130E43900C838E8 /* PBGitHistoryGrapher.m in Sources */,
 				D8E105471157C18200FC28A4 /* PBQLTextView.m in Sources */,
+				D8FBCF19115FA20C0098676A /* PBGitSHA.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
diff --git a/PBGitCommit.h b/PBGitCommit.h
index 9e4da8d..e77ee32 100644
--- a/PBGitCommit.h
+++ b/PBGitCommit.h
@@ -10,23 +10,21 @@
 #import "PBGitRepository.h"
 #import "PBGitTree.h"
 #import "PBGitRefish.h"
-#include "git/oid.h"
+#import "PBGitSHA.h"
 
 
 extern NSString * const kGitXCommitType;
 
 
 @interface PBGitCommit : NSObject <PBGitRefish> {
-	git_oid sha;
-	git_oid *parentShas;
-	int nParents;
+	PBGitSHA *sha;
 
 	NSString* subject;
 	NSString* author;
 	NSString *committer;
 	NSString* details;
 	NSString *_patch;
-	NSArray* parents;
+	NSArray *parents;
 	NSString *realSHA;
 
 	int timestamp;
@@ -35,8 +33,8 @@ extern NSString * const kGitXCommitType;
 	PBGitRepository* repository;
 }
 
-+ (id) commitWithRepository:(PBGitRepository*)repo andSha:(git_oid)newSha;
-- (id) initWithRepository:(PBGitRepository *)repo andSha:(git_oid)sha;
++ (PBGitCommit *)commitWithRepository:(PBGitRepository*)repo andSha:(PBGitSHA *)newSha;
+- (id)initWithRepository:(PBGitRepository *)repo andSha:(PBGitSHA *)newSha;
 
 - (void) addRef:(PBGitRef *)ref;
 - (void) removeRef:(id)ref;
@@ -51,14 +49,13 @@ extern NSString * const kGitXCommitType;
 - (NSString *) shortName;
 - (NSString *) refishType;
 
-@property (readonly) git_oid *sha;
+@property (readonly) PBGitSHA *sha;
 @property (copy) NSString* subject;
 @property (copy) NSString* author;
 @property (copy) NSString *committer;
-@property (readonly) NSArray* parents; // TODO: remove this and its uses
+@property (retain) NSArray *parents;
 
-@property (assign) git_oid *parentShas;
-@property (assign) int nParents, timestamp;
+@property (assign) int timestamp;
 
 @property (retain) NSMutableArray* refs;
 @property (readonly) NSDate *date;
diff --git a/PBGitCommit.m b/PBGitCommit.m
index 6bb9d56..ac2bd1f 100644
--- a/PBGitCommit.m
+++ b/PBGitCommit.m
@@ -7,6 +7,7 @@
 //
 
 #import "PBGitCommit.h"
+#import "PBGitSHA.h"
 #import "PBGitDefaults.h"
 
 
@@ -15,24 +16,11 @@ NSString * const kGitXCommitType = @"commit";
 
 @implementation PBGitCommit
 
-@synthesize repository, subject, timestamp, author, parentShas, nParents, sign, lineInfo;
+@synthesize repository, subject, timestamp, author, sign, lineInfo;
+@synthesize sha;
+@synthesize parents;
 @synthesize committer;
 
-- (NSArray *) parents
-{
-	if (nParents == 0)
-		return NULL;
-
-	int i;
-	NSMutableArray *p = [NSMutableArray arrayWithCapacity:nParents];
-	for (i = 0; i < nParents; ++i)
-	{
-		char *s = git_oid_mkhex(parentShas + i);
-		[p addObject:[NSString stringWithUTF8String:s]];
-		free(s);
-	}
-	return p;
-}
 
 - (NSDate *)date
 {
@@ -50,17 +38,12 @@ NSString * const kGitXCommitType = @"commit";
 	return self.tree.children;
 }
 
-- (git_oid *)sha
++ (PBGitCommit *)commitWithRepository:(PBGitRepository*)repo andSha:(PBGitSHA *)newSha
 {
-	return &sha;
+	return [[self alloc] initWithRepository:repo andSha:newSha];
 }
 
-+ commitWithRepository:(PBGitRepository*)repo andSha:(git_oid)newSha
-{
-	return [[[self alloc] initWithRepository:repo andSha:newSha] autorelease];
-}
-
-- initWithRepository:(PBGitRepository*) repo andSha:(git_oid)newSha
+- (id)initWithRepository:(PBGitRepository*) repo andSha:(PBGitSHA *)newSha
 {
 	details = nil;
 	repository = repo;
@@ -70,27 +53,18 @@ NSString * const kGitXCommitType = @"commit";
 
 - (NSString *)realSha
 {
-	if (!realSHA) {
-		char *hex = git_oid_mkhex(&sha);
-		realSHA = [NSString stringWithUTF8String:hex];
-		free(hex);
-	}
-
-	return realSHA;
+	return sha.string;
 }
 
-- (BOOL) isOnSameBranchAs:(PBGitCommit *)other
+- (BOOL) isOnSameBranchAs:(PBGitCommit *)otherCommit
 {
-	if (!other)
+	if (!otherCommit)
 		return NO;
 
-	NSString *mySHA = [self realSha];
-	NSString *otherSHA = [other realSha];
-
-	if ([otherSHA isEqualToString:mySHA])
+	if ([self isEqual:otherCommit])
 		return YES;
 
-	return [repository isOnSameBranch:otherSHA asSHA:mySHA];
+	return [repository isOnSameBranch:otherCommit.sha asSHA:self.sha];
 }
 
 - (BOOL) isOnHeadBranch
@@ -98,6 +72,19 @@ NSString * const kGitXCommitType = @"commit";
 	return [self isOnSameBranchAs:[repository headCommit]];
 }
 
+- (BOOL)isEqual:(id)otherCommit
+{
+	if (![otherCommit isMemberOfClass:[PBGitCommit class]])
+		return NO;
+
+	return [self.sha isEqual:[(PBGitCommit *)otherCommit sha]];
+}
+
+- (NSUInteger)hash
+{
+	return [self.sha hash];
+}
+
 // FIXME: Remove this method once it's unused.
 - (NSString*) details
 {
@@ -150,17 +137,16 @@ NSString * const kGitXCommitType = @"commit";
 
 - (NSMutableArray *)refs
 {
-	return [[repository refs] objectForKey:[self realSha]];
+	return [[repository refs] objectForKey:[self sha]];
 }
 
 - (void) setRefs:(NSMutableArray *)refs
 {
-	[[repository refs] setObject:refs forKey:[self realSha]];
+	[[repository refs] setObject:refs forKey:[self sha]];
 }
 
 - (void)finalize
 {
-	free(parentShas);
 	[super finalize];
 }
 
diff --git a/PBGitGrapher.mm b/PBGitGrapher.mm
index f9daf84..abd6327 100644
--- a/PBGitGrapher.mm
+++ b/PBGitGrapher.mm
@@ -39,8 +39,10 @@ void add_line(struct PBGitGraphLine *lines, int *nLines, int upper, int from, in
 	int i = 0, newPos = -1;
 	std::list<PBGitLane *> *currentLanes = new std::list<PBGitLane *>;
 	std::list<PBGitLane *> *previousLanes = (std::list<PBGitLane *> *)pl;
+	NSArray *parents = [commit parents];
+	int nParents = [parents count];
 
-	int maxLines = (previousLanes->size() + commit.nParents + 2) * 2;
+	int maxLines = (previousLanes->size() + nParents + 2) * 2;
 	struct PBGitGraphLine *lines = (struct PBGitGraphLine *)malloc(sizeof(struct PBGitGraphLine) * maxLines);
 	int currentLine = 0;
 
@@ -55,14 +57,14 @@ void add_line(struct PBGitGraphLine *lines, int *nLines, int upper, int from, in
 			i++;
 			// This is our commit! We should do a "merge": move the line from
 			// our upperMapping to their lowerMapping
-			if ((*it)->isCommit([commit sha])) {
+			if ((*it)->isCommit([[commit sha] oid])) {
 				if (!didFirst) {
 					didFirst = YES;
 					currentLanes->push_back(*it);
 					currentLane = currentLanes->back();
 					newPos = currentLanes->size();
 					add_line(lines, &currentLine, 1, i, newPos,(*it)->index());
-					if (commit.nParents)
+					if (nParents)
 						add_line(lines, &currentLine, 0, newPos, newPos,(*it)->index());
 				}
 				else {
@@ -84,8 +86,9 @@ void add_line(struct PBGitGraphLine *lines, int *nLines, int upper, int from, in
 	//Add your own parents
 
 	// If we already did the first parent, don't do so again
-	if (!didFirst && currentLanes->size() < MAX_LANES && commit.nParents) {
-		PBGitLane *newLane = new PBGitLane(commit.parentShas);
+	if (!didFirst && currentLanes->size() < MAX_LANES && nParents) {
+		git_oid parentOID = [[parents objectAtIndex:0] oid];
+		PBGitLane *newLane = new PBGitLane(&parentOID);
 		currentLanes->push_back(newLane);
 		newPos = currentLanes->size();
 		add_line(lines, &currentLine, 0, newPos, newPos, newLane->index());
@@ -97,15 +100,15 @@ void add_line(struct PBGitGraphLine *lines, int *nLines, int upper, int from, in
 	// This boolean will tell us if that happened
 	BOOL addedParent = NO;
 
-	int parentIndex;
-	for (parentIndex = 1; parentIndex < commit.nParents; ++parentIndex) {
-		git_oid *parent = commit.parentShas + parentIndex;
+	int parentIndex = 0;
+	for (parentIndex = 1; parentIndex < nParents; ++parentIndex) {
+		git_oid parentOID = [[parents objectAtIndex:parentIndex] oid];
 		int i = 0;
 		BOOL was_displayed = NO;
 		std::list<PBGitLane *>::iterator it = currentLanes->begin();
 		for (; it != currentLanes->end(); ++it) {
 			i++;
-			if ((*it)->isCommit(parent)) {
+			if ((*it)->isCommit(parentOID)) {
 				add_line(lines, &currentLine, 0, i, newPos,(*it)->index());
 				was_displayed = YES;
 				break;
@@ -119,7 +122,7 @@ void add_line(struct PBGitGraphLine *lines, int *nLines, int upper, int from, in
 
 		// Really add this parent
 		addedParent = YES;
-		PBGitLane *newLane = new PBGitLane(parent);
+		PBGitLane *newLane = new PBGitLane(&parentOID);
 		currentLanes->push_back(newLane);
 		add_line(lines, &currentLine, 0, currentLanes->size(), newPos, newLane->index());
 	}
@@ -138,8 +141,8 @@ void add_line(struct PBGitGraphLine *lines, int *nLines, int upper, int from, in
 		previous.numColumns = currentLanes->size();
 
 	// Update the current lane to point to the new parent
-	if (currentLane && commit.nParents > 0)
-		currentLane->setSha(commit.parentShas[0]);
+	if (currentLane && nParents > 0)
+		currentLane->setSha([[parents objectAtIndex:0] oid]);
 	else
 		currentLanes->remove(currentLane);
 
diff --git a/PBGitHistoryController.h b/PBGitHistoryController.h
index 3c92168..6489930 100644
--- a/PBGitHistoryController.h
+++ b/PBGitHistoryController.h
@@ -17,6 +17,7 @@
 @class PBRefController;
 @class QLPreviewPanel;
 @class PBCommitList;
+@class PBGitSHA;
 
 @interface PBGitHistoryController : PBViewController {
 	IBOutlet PBRefController *refController;
@@ -58,7 +59,7 @@
 - (IBAction) setTreeView:(id)sender;
 - (IBAction) setBranchFilter:(id)sender;
 
-- (void) selectCommit: (NSString*) commit;
+- (void)selectCommit:(PBGitSHA *)commit;
 - (IBAction) refresh:(id)sender;
 - (IBAction) toggleQLPreviewPanel:(id)sender;
 - (IBAction) openSelectedFile:(id)sender;
diff --git a/PBGitHistoryController.m b/PBGitHistoryController.m
index 9e0fafb..9d5a428 100644
--- a/PBGitHistoryController.m
+++ b/PBGitHistoryController.m
@@ -236,7 +236,7 @@
 		if ([repository.currentBranch isSimpleRef])
 			[self selectCommit:[repository shaForRef:[repository.currentBranch ref]]];
 		else
-			[self selectCommit:[[self firstCommit] realSha]];
+			[self selectCommit:[[self firstCommit] sha]];
 		return;
 	}
 
@@ -385,9 +385,9 @@
     commitList.useAdjustScroll = NO;
 }
 
-- (NSArray *) selectedObjectsForSHA:(NSString *)commitSHA
+- (NSArray *) selectedObjectsForSHA:(PBGitSHA *)commitSHA
 {
-	NSPredicate *selection = [NSPredicate predicateWithFormat:@"realSha == %@", commitSHA];
+	NSPredicate *selection = [NSPredicate predicateWithFormat:@"sha == %@", commitSHA];
 	NSArray *selectedCommits = [[commitController content] filteredArrayUsingPredicate:selection];
 
 	if (([selectedCommits count] == 0) && [self firstCommit])
@@ -396,9 +396,9 @@
 	return selectedCommits;
 }
 
-- (void) selectCommit:(NSString *)commitSHA
+- (void)selectCommit:(PBGitSHA *)commitSHA
 {
-	if (!forceSelectionUpdate && [[selectedCommit realSha] isEqualToString:commitSHA])
+	if (!forceSelectionUpdate && [[selectedCommit sha] isEqual:commitSHA])
 		return;
 
 	NSInteger oldIndex = [[commitController selectionIndexes] firstIndex];
@@ -521,7 +521,7 @@
 	PBGitRef *headRef = [[repository headRef] ref];
 	NSString *headRefName = [headRef shortName];
 	NSString *diffTitle = [NSString stringWithFormat:@"Diff %@ with %@", multiple ? @"files" : @"file", headRefName];
-	BOOL isHead = [[selectedCommit realSha] isEqualToString:[repository headSHA]];
+	BOOL isHead = [[selectedCommit sha] isEqual:[repository headSHA]];
 	NSMenuItem *diffItem = [[NSMenuItem alloc] initWithTitle:diffTitle
 													  action:isHead ? nil : @selector(diffFilesAction:)
 											   keyEquivalent:@""];
diff --git a/PBGitHistoryGrapher.m b/PBGitHistoryGrapher.m
index 4769950..891d342 100644
--- a/PBGitHistoryGrapher.m
+++ b/PBGitHistoryGrapher.m
@@ -8,6 +8,7 @@
 
 #import "PBGitHistoryGrapher.h"
 #import "PBGitGrapher.h"
+#import "PBGitSHA.h"
 
 
 @implementation PBGitHistoryGrapher
@@ -41,13 +42,13 @@
 	NSInteger counter = 0;
 
 	for (PBGitCommit *commit in revList) {
-		NSString *commitSHA = [commit realSha];
+		PBGitSHA *commitSHA = [commit sha];
 		if (viewAllBranches || [searchSHAs containsObject:commitSHA]) {
 			[grapher decorateCommit:commit];
 			[commits addObject:commit];
 			if (!viewAllBranches) {
 				[searchSHAs removeObject:commitSHA];
-				[searchSHAs addObjectsFromArray:commit.parents];
+				[searchSHAs addObjectsFromArray:[commit parents]];
 			}
 		}
 		if (++counter % 2000 == 0) {
diff --git a/PBGitHistoryList.h b/PBGitHistoryList.h
index 93fdcd3..9f00a66 100644
--- a/PBGitHistoryList.h
+++ b/PBGitHistoryList.h
@@ -14,6 +14,7 @@
 @class PBGitRef;
 @class PBGitRevList;
 @class PBGitHistoryGrapher;
+@class PBGitSHA;
 
 @interface PBGitHistoryList : NSObject {
 	PBGitRepository *repository;
@@ -21,7 +22,7 @@
 	PBGitRevList *projectRevList;
 	PBGitRevList *currentRevList;
 
-	NSString *lastSHA;
+	PBGitSHA *lastSHA;
 	NSSet *lastRefSHAs;
 	NSInteger lastBranchFilter;
 	PBGitRef *lastRemoteRef;
diff --git a/PBGitHistoryList.m b/PBGitHistoryList.m
index 59cb3c4..017a757 100644
--- a/PBGitHistoryList.m
+++ b/PBGitHistoryList.m
@@ -11,6 +11,7 @@
 #import "PBGitRevList.h"
 #import "PBGitGrapher.h"
 #import "PBGitHistoryGrapher.h"
+#import "PBGitSHA.h"
 
 
 
@@ -158,7 +159,7 @@
 	NSMutableSet *baseCommitSHAs = [NSMutableSet set];
 	NSDictionary *refs = repository.refs;
 
-	for (NSString *sha in refs)
+	for (PBGitSHA *sha in refs)
 		for (PBGitRef *ref in [refs objectForKey:sha])
 			if ([ref isBranch] || [ref isTag])
 				[baseCommitSHAs addObject:sha];
@@ -177,7 +178,7 @@
 
 	PBGitRef *remoteRef = [[repository.currentBranch ref] remoteRef];
 
-	for (NSString *sha in refs)
+	for (PBGitSHA *sha in refs)
 		for (PBGitRef *ref in [refs objectForKey:sha])
 			if ([remoteRef isEqualToRef:[ref remoteRef]])
 				[baseCommitSHAs addObject:sha];
@@ -193,7 +194,7 @@
 			return [NSMutableSet setWithObject:lastSHA];
 		else if ([repository.currentBranch isSimpleRef]) {
 			PBGitRef *currentRef = [repository.currentBranch ref];
-			NSString *sha = [repository shaForRef:currentRef];
+			PBGitSHA *sha = [repository shaForRef:currentRef];
 			if (sha)
 				return [NSMutableSet setWithObject:sha];
 		}
@@ -267,8 +268,8 @@
 		return NO;
 	}
 
-	NSString *revSHA = [repository shaForRef:[rev ref]];
-	if ([revSHA isEqualToString:lastSHA] && (lastBranchFilter == repository.currentBranchFilter))
+	PBGitSHA *revSHA = [repository shaForRef:[rev ref]];
+	if ([revSHA isEqual:lastSHA] && (lastBranchFilter == repository.currentBranchFilter))
 		return NO;
 
 	lastBranchFilter = repository.currentBranchFilter;
@@ -341,6 +342,7 @@
 - (void) removeObservers
 {
 	[repository removeObserver:self forKeyPath:@"currentBranch"];
+	[repository removeObserver:self forKeyPath:@"currentBranchFilter"];
 	[repository removeObserver:self forKeyPath:@"hasChanged"];
 
 	if (currentRevList) {
diff --git a/PBGitLane.h b/PBGitLane.h
index 57d59c8..94b59a2 100644
--- a/PBGitLane.h
+++ b/PBGitLane.h
@@ -33,9 +33,9 @@ public:
 		d_index = s_colorIndex++;
 	}
 	
-	bool isCommit(git_oid *sha) const
+	bool isCommit(git_oid sha) const
 	{
-		return !git_oid_cmp(&d_sha, sha);
+		return !git_oid_cmp(&d_sha, &sha);
 	}
 	
 	void setSha(git_oid sha);
diff --git a/PBGitRepository.h b/PBGitRepository.h
index 0236a06..25176cd 100644
--- a/PBGitRepository.h
+++ b/PBGitRepository.h
@@ -38,6 +38,7 @@ static NSString * PBStringFromBranchFilterType(PBGitXBranchFilterType type) {
 
 @class PBGitWindowController;
 @class PBGitCommit;
+@class PBGitSHA;
 
 @interface PBGitRepository : NSDocument {
 	PBGitHistoryList* revisionList;
@@ -50,7 +51,7 @@ static NSString * PBStringFromBranchFilterType(PBGitXBranchFilterType type) {
 	NSMutableDictionary *refs;
 
 	PBGitRevSpecifier *_headRef; // Caching
-	NSString* _headSha;
+	PBGitSHA* _headSha;
 }
 
 - (void) cloneRepositoryToPath:(NSString *)path bare:(BOOL)isBare;
@@ -92,17 +93,17 @@ static NSString * PBStringFromBranchFilterType(PBGitXBranchFilterType type) {
 - (void) reloadRefs;
 - (void) addRef:(PBGitRef *)ref fromParameters:(NSArray *)params;
 - (void) lazyReload;
-- (PBGitRevSpecifier*) headRef;
-- (NSString *) headSHA;
-- (PBGitCommit *) headCommit;
-- (NSString *) shaForRef:(PBGitRef *)ref;
-- (PBGitCommit *) commitForRef:(PBGitRef *)ref;
-- (PBGitCommit *) commitForSHA:(NSString *)sha;
-- (BOOL) isOnSameBranch:(NSString *)baseSHA asSHA:(NSString *)testSHA;
-- (BOOL) isSHAOnHeadBranch:(NSString *)testSHA;
-- (BOOL) isRefOnHeadBranch:(PBGitRef *)testRef;
-- (BOOL) checkRefFormat:(NSString *)refName;
-- (BOOL) refExists:(PBGitRef *)ref;
+- (PBGitRevSpecifier*)headRef;
+- (PBGitSHA *)headSHA;
+- (PBGitCommit *)headCommit;
+- (PBGitSHA *)shaForRef:(PBGitRef *)ref;
+- (PBGitCommit *)commitForRef:(PBGitRef *)ref;
+- (PBGitCommit *)commitForSHA:(PBGitSHA *)sha;
+- (BOOL)isOnSameBranch:(PBGitSHA *)baseSHA asSHA:(PBGitSHA *)testSHA;
+- (BOOL)isSHAOnHeadBranch:(PBGitSHA *)testSHA;
+- (BOOL)isRefOnHeadBranch:(PBGitRef *)testRef;
+- (BOOL)checkRefFormat:(NSString *)refName;
+- (BOOL)refExists:(PBGitRef *)ref;
 
 - (NSArray *) remotes;
 - (BOOL) hasRemotes;
diff --git a/PBGitRepository.m b/PBGitRepository.m
index f401aa6..f9f9175 100644
--- a/PBGitRepository.m
+++ b/PBGitRepository.m
@@ -218,11 +218,11 @@ NSString* PBGitRepositoryErrorDomain = @"GitXErrorDomain";
 {
 	NSString* type = [components objectAtIndex:1];
 
-	NSString* sha;
+	PBGitSHA *sha;
 	if ([type isEqualToString:@"tag"] && [components count] == 4)
-		sha = [components objectAtIndex:3];
+		sha = [PBGitSHA shaWithString:[components objectAtIndex:3]];
 	else
-		sha = [components objectAtIndex:2];
+		sha = [PBGitSHA shaWithString:[components objectAtIndex:2]];
 
 	NSMutableArray* curRefs;
 	if (curRefs = [refs objectForKey:sha])
@@ -293,7 +293,7 @@ NSString* PBGitRepositoryErrorDomain = @"GitXErrorDomain";
 	return _headRef;
 }
 
-- (NSString *) headSHA
+- (PBGitSHA *)headSHA
 {
 	if (! _headSha)
 		[self headRef];
@@ -301,17 +301,17 @@ NSString* PBGitRepositoryErrorDomain = @"GitXErrorDomain";
 	return _headSha;
 }
 
-- (PBGitCommit *) headCommit
+- (PBGitCommit *)headCommit
 {
 	return [self commitForSHA:[self headSHA]];
 }
 
-- (NSString *) shaForRef:(PBGitRef *)ref
+- (PBGitSHA *)shaForRef:(PBGitRef *)ref
 {
 	if (!ref)
 		return nil;
 
-	for (NSString *sha in refs)
+	for (PBGitSHA *sha in refs)
 		for (PBGitRef *existingRef in [refs objectForKey:sha])
 			if ([existingRef isEqualToRef:ref])
 				return sha;
@@ -322,10 +322,10 @@ NSString* PBGitRepositoryErrorDomain = @"GitXErrorDomain";
 	if (retValue || [shaForRef isEqualToString:@""])
 		return nil;
 
-	return shaForRef;
+	return [PBGitSHA shaWithString:shaForRef];
 }
 
-- (PBGitCommit *) commitForRef:(PBGitRef *)ref
+- (PBGitCommit *)commitForRef:(PBGitRef *)ref
 {
 	if (!ref)
 		return nil;
@@ -333,7 +333,7 @@ NSString* PBGitRepositoryErrorDomain = @"GitXErrorDomain";
 	return [self commitForSHA:[self shaForRef:ref]];
 }
 
-- (PBGitCommit *) commitForSHA:(NSString *)sha
+- (PBGitCommit *)commitForSHA:(PBGitSHA *)sha
 {
 	if (!sha)
 		return nil;
@@ -344,18 +344,18 @@ NSString* PBGitRepositoryErrorDomain = @"GitXErrorDomain";
         revList = revisionList.projectCommits;
     }
 	for (PBGitCommit *commit in revList)
-		if ([[commit realSha] isEqualToString:sha])
+		if ([[commit sha] isEqual:sha])
 			return commit;
 
 	return nil;
 }
 
-- (BOOL) isOnSameBranch:(NSString *)branchSHA asSHA:(NSString *)testSHA
+- (BOOL)isOnSameBranch:(PBGitSHA *)branchSHA asSHA:(PBGitSHA *)testSHA
 {
 	if (!branchSHA || !testSHA)
 		return NO;
 
-	if ([testSHA isEqualToString:branchSHA])
+	if ([testSHA isEqual:branchSHA])
 		return YES;
 
 	NSArray *revList = revisionList.projectCommits;
@@ -363,34 +363,34 @@ NSString* PBGitRepositoryErrorDomain = @"GitXErrorDomain";
 	NSMutableSet *searchSHAs = [NSMutableSet setWithObject:branchSHA];
 
 	for (PBGitCommit *commit in revList) {
-		NSString *commitSHA = [commit realSha];
+		PBGitSHA *commitSHA = [commit sha];
 		if ([searchSHAs containsObject:commitSHA]) {
-			if ([testSHA isEqualToString:commitSHA])
+			if ([testSHA isEqual:commitSHA])
 				return YES;
 			[searchSHAs removeObject:commitSHA];
 			[searchSHAs addObjectsFromArray:commit.parents];
 		}
-		else if ([testSHA isEqualToString:commitSHA])
+		else if ([testSHA isEqual:commitSHA])
 			return NO;
 	}
 
 	return NO;
 }
 
-- (BOOL) isSHAOnHeadBranch:(NSString *)testSHA
+- (BOOL)isSHAOnHeadBranch:(PBGitSHA *)testSHA
 {
 	if (!testSHA)
 		return NO;
 
-	NSString *headSHA = [self headSHA];
+	PBGitSHA *headSHA = [self headSHA];
 
-	if ([testSHA isEqualToString:headSHA])
+	if ([testSHA isEqual:headSHA])
 		return YES;
 
 	return [self isOnSameBranch:headSHA asSHA:testSHA];
 }
 
-- (BOOL) isRefOnHeadBranch:(PBGitRef *)testRef
+- (BOOL)isRefOnHeadBranch:(PBGitRef *)testRef
 {
 	if (!testRef)
 		return NO;
diff --git a/PBGitRevList.mm b/PBGitRevList.mm
index 4a033fb..ea0933d 100644
--- a/PBGitRevList.mm
+++ b/PBGitRevList.mm
@@ -12,7 +12,6 @@
 #import "PBGitGrapher.h"
 #import "PBGitRevSpecifier.h"
 
-#include "git/oid.h"
 #include <ext/stdio_filebuf.h>
 #include <iostream>
 #include <string>
@@ -140,7 +139,7 @@ using namespace std;
 
 		git_oid oid;
 		git_oid_mkstr(&oid, sha.c_str());
-		PBGitCommit* newCommit = [[PBGitCommit alloc] initWithRepository:repository andSha:oid];
+		PBGitCommit *newCommit = [PBGitCommit commitWithRepository:repository andSha:[PBGitSHA shaWithOID:oid]];
 
 		string author;
 		getline(stream, author, '\1');
@@ -160,13 +159,12 @@ using namespace std;
 				continue;
 			}
 			int nParents = (parentString.size() + 1) / 41;
-			git_oid *parents = (git_oid *)malloc(sizeof(git_oid) * nParents);
+			NSMutableArray *parents = [NSMutableArray arrayWithCapacity:nParents];
 			int parentIndex;
 			for (parentIndex = 0; parentIndex < nParents; ++parentIndex)
-				git_oid_mkstr(parents + parentIndex, parentString.substr(parentIndex * 41, 40).c_str());
-			
-			newCommit.parentShas = parents;
-			newCommit.nParents = nParents;
+				[parents addObject:[PBGitSHA shaWithCString:parentString.substr(parentIndex * 41, 40).c_str()]];
+
+			[newCommit setParents:parents];
 		}
 
 		int time;
diff --git a/PBGitRevisionCell.m b/PBGitRevisionCell.m
index abbf29c..17e5b16 100644
--- a/PBGitRevisionCell.m
+++ b/PBGitRevisionCell.m
@@ -59,12 +59,12 @@
 
 - (BOOL) isCurrentCommit
 {
-	NSString* thisSha = [self.objectValue realSha];
+	PBGitSHA *thisSha = [self.objectValue sha];
 
 	PBGitRepository* repository = [self.objectValue repository];
-	NSString* currentSha = [repository headSHA];
+	PBGitSHA *currentSha = [repository headSHA];
 
-	return [ currentSha isEqualToString : thisSha ];
+	return [currentSha isEqual:thisSha];
 }
 
 - (void) drawCircleInRect: (NSRect) r
diff --git a/PBGitSHA.h b/PBGitSHA.h
new file mode 100644
index 0000000..f222911
--- /dev/null
+++ b/PBGitSHA.h
@@ -0,0 +1,28 @@
+//
+//  PBGitSHA.h
+//  GitX
+//
+//  Created by BrotherBard on 3/28/10.
+//  Copyright 2010 BrotherBard. All rights reserved.
+//
+
+#import <Cocoa/Cocoa.h>
+#include "git/oid.h"
+
+
+@interface PBGitSHA : NSObject <NSCopying> {
+	git_oid oid;
+	NSString *string;
+}
+
+
++ (PBGitSHA *)shaWithOID:(git_oid)oid;
++ (PBGitSHA *)shaWithString:(NSString *)shaString;
++ (PBGitSHA *)shaWithCString:(const char *)shaCString;
+
+- (BOOL)isEqualToOID:(git_oid)other_oid;
+
+@property (readonly) git_oid oid;
+@property (readonly) NSString *string;
+
+@end
diff --git a/PBGitSHA.m b/PBGitSHA.m
new file mode 100644
index 0000000..6aff86f
--- /dev/null
+++ b/PBGitSHA.m
@@ -0,0 +1,139 @@
+//
+//  PBGitSHA.m
+//  GitX
+//
+//  Created by BrotherBard on 3/28/10.
+//  Copyright 2010 BrotherBard. All rights reserved.
+//
+
+#import "PBGitSHA.h"
+
+
+@interface PBGitSHA ()
+
+- (id)initWithOID:(git_oid)g_oid;
+
+@end
+
+
+@implementation PBGitSHA
+
+
+@synthesize oid;
+@synthesize string;
+
+
++ (PBGitSHA *)shaWithOID:(git_oid)oid
+{
+	return [[PBGitSHA alloc] initWithOID:oid];
+}
+
+
++ (PBGitSHA *)shaWithString:(NSString *)shaString
+{
+	git_oid oid;
+	int err = git_oid_mkstr(&oid, [shaString UTF8String]);
+	if (err == GIT_ENOTOID)
+		return nil;
+
+	return [self shaWithOID:oid];
+}
+
+
++ (PBGitSHA *)shaWithCString:(const char *)shaCString
+{
+	git_oid oid;
+	int err = git_oid_mkstr(&oid, shaCString);
+	if (err == GIT_ENOTOID)
+		return nil;
+
+	return [self shaWithOID:oid];
+}
+
+
++ (BOOL)isSelectorExcludedFromWebScript:(SEL)aSelector
+{
+	return NO;
+}
+
+
++ (BOOL)isKeyExcludedFromWebScript:(const char *)name
+{
+	return NO;
+}
+
+
+
+#pragma mark -
+#pragma mark PBGitSHA
+
+- (id)initWithOID:(git_oid)g_oid
+{
+	self = [super init];
+	if (!self)
+		return nil;
+
+	oid = g_oid;
+
+	return self;
+}
+
+
+- (NSString *)string
+{
+	if (!string) {
+		char *hex = git_oid_mkhex(&oid);
+		if (hex == NULL)
+			return nil;
+		string = [NSString stringWithUTF8String:hex];
+		free(hex);
+	}
+
+	return string;
+}
+
+
+- (BOOL)isEqual:(id)otherSHA
+{
+	if (self == otherSHA)
+		return YES;
+
+	git_oid other_oid = [(PBGitSHA *)otherSHA oid];
+	return git_oid_cmp(&oid, &other_oid) == 0;
+}
+
+
+- (BOOL)isEqualToOID:(git_oid)other_oid
+{
+	return git_oid_cmp(&oid, &other_oid) == 0;
+}
+
+
+- (NSUInteger)hash
+{
+	NSUInteger hash;
+	memcpy(&hash, &(oid.id), sizeof(NSUInteger));
+
+	return hash;
+}
+
+
+- (NSString *)description
+{
+	return [self string];
+}
+
+
+
+#pragma mark <NSCopying>
+
+- (id)copyWithZone:(NSZone *)zone
+{
+	git_oid oidCopy;
+	git_oid_cpy(&oidCopy, &oid);
+    PBGitSHA *copy = [[[self class] allocWithZone:zone] initWithOID:oidCopy];
+
+	return copy;
+}
+
+@end
diff --git a/PBRefMenuItem.m b/PBRefMenuItem.m
index 8a571d5..e7b7c0b 100644
--- a/PBRefMenuItem.m
+++ b/PBRefMenuItem.m
@@ -145,7 +145,7 @@
 
 	NSString *headBranchName = [[[commit.repository headRef] ref] shortName];
 	BOOL isOnHeadBranch = [commit isOnHeadBranch];
-	BOOL isHead = [[commit realSha] isEqualToString:[commit.repository headSHA]];
+	BOOL isHead = [[commit sha] isEqual:[commit.repository headSHA]];
 
 	[items addObject:[PBRefMenuItem itemWithTitle:@"Checkout Commit" action:@selector(checkout:) enabled:YES]];
 	[items addObject:[PBRefMenuItem separatorItem]];
diff --git a/PBWebHistoryController.h b/PBWebHistoryController.h
index 749725a..f42a42e 100644
--- a/PBWebHistoryController.h
+++ b/PBWebHistoryController.h
@@ -13,11 +13,15 @@
 #import "PBGitHistoryController.h"
 #import "PBRefContextDelegate.h"
 
+
+@class PBGitSHA;
+
+
 @interface PBWebHistoryController : PBWebController {
 	IBOutlet PBGitHistoryController* historyController;
 	IBOutlet id<PBRefContextDelegate> contextMenuDelegate;
 
-	NSString* currentSha;
+	PBGitSHA* currentSha;
 	NSString* diff;
 }
 
diff --git a/PBWebHistoryController.m b/PBWebHistoryController.m
index 08279cf..f0c533d 100644
--- a/PBWebHistoryController.m
+++ b/PBWebHistoryController.m
@@ -8,6 +8,7 @@
 
 #import "PBWebHistoryController.h"
 #import "PBGitDefaults.h"
+#import "PBGitSHA.h"
 
 @implementation PBWebHistoryController
 
@@ -23,7 +24,7 @@
 
 - (void) didLoad
 {
-	currentSha = @"";
+	currentSha = nil;
 	[self changeContentTo: historyController.webCommit];
 }
 
@@ -41,7 +42,7 @@
 		return;
 
 	// The sha is the same, but refs may have changed.. reload it lazy
-	if ([currentSha isEqualToString: [content realSha]])
+	if ([currentSha isEqual:[content sha]])
 	{
 		[[self script] callWebScriptMethod:@"reload" withArguments: nil];
 		return;
@@ -54,13 +55,13 @@
 		[self performSelector:_cmd withObject:content afterDelay:0.05];
 		return;
 	}
-	currentSha = [content realSha];
+	currentSha = [content sha];
 
 	// Now we load the extended details. We used to do this in a separate thread,
 	// but this caused some funny behaviour because NSTask's and NSThread's don't really
 	// like each other. Instead, just do it async.
 
-	NSMutableArray *taskArguments = [NSMutableArray arrayWithObjects:@"show", @"--pretty=raw", @"-M", @"--no-color", currentSha, nil];
+	NSMutableArray *taskArguments = [NSMutableArray arrayWithObjects:@"show", @"--pretty=raw", @"-M", @"--no-color", [currentSha string], nil];
 	if (![PBGitDefaults showWhitespaceDifferences])
 		[taskArguments insertObject:@"-w" atIndex:1];
 
@@ -90,9 +91,9 @@
 	[[view windowScriptObject] callWebScriptMethod:@"loadCommitDetails" withArguments:[NSArray arrayWithObject:details]];
 }
 
-- (void) selectCommit: (NSString*) sha
+- (void)selectCommit:(NSString *)sha
 {
-	[historyController selectCommit:sha];
+	[historyController selectCommit:[PBGitSHA shaWithString:sha]];
 }
 
 - (void) sendKey: (NSString*) key
diff --git a/html/views/history/history.js b/html/views/history/history.js
index 4c9db52..c90c0c2 100644
--- a/html/views/history/history.js
+++ b/html/views/history/history.js
@@ -209,7 +209,7 @@ var loadCommit = function(commitObject, currentRef) {
 		var newRow = $("commit_header").insertRow(-1);
 		newRow.innerHTML = "<td class='property_name'>Parent:</td><td>" +
 			"<a href='' onclick='selectCommit(this.innerHTML); return false;'>" +
-			commit.parents[i] + "</a></td>";
+			commit.parents[i].string + "</a></td>";
 	}
 
 	commit.notificationID = setTimeout(function() {