diff --git a/PBGitSidebarController.m b/PBGitSidebarController.m
index dad7de1..930a47c 100644
--- a/PBGitSidebarController.m
+++ b/PBGitSidebarController.m
@@ -342,6 +342,11 @@ static NSString * const kObservingContextSubmodules = @"submodulesChanged";
 	[cell setImage:[item icon]];
 }
 
+- (NSString *)outlineView:(NSOutlineView *)outlineView toolTipForCell:(NSCell *)cell rect:(NSRectPointer)rect tableColumn:(NSTableColumn *)tc item:(id)item mouseLocation:(NSPoint)mouseLocation
+{
+	return [item helpText];
+}
+
 - (BOOL)outlineView:(NSOutlineView *)outlineView shouldSelectItem:(id)item
 {
 	return ![item isGroupItem];
diff --git a/PBSourceViewItem.h b/PBSourceViewItem.h
index 1547fd6..ec3bd4d 100644
--- a/PBSourceViewItem.h
+++ b/PBSourceViewItem.h
@@ -14,7 +14,7 @@
 @interface PBSourceViewItem : NSObject {
 	NSMutableArray *children;
 
-	NSString *title;
+	NSString *title, *helpText;
 	PBGitRevSpecifier *revSpecifier;
 	PBSourceViewItem *parent;
 
@@ -43,6 +43,7 @@
 - (PBGitRef *) ref;
 
 @property(retain) NSString *title;
+@property(retain) NSString *helpText;
 @property(readonly) NSMutableArray *children;
 @property(assign) BOOL isGroupItem, isUncollapsible;
 @property(retain) PBGitRevSpecifier *revSpecifier;