diff --git a/PBGitRevisionCell.m b/PBGitRevisionCell.m
index d76334bf6..b1aa847cd 100644
--- a/PBGitRevisionCell.m
+++ b/PBGitRevisionCell.m
@@ -209,6 +209,7 @@ - (void) drawRefsInRect: (NSRect *)refRect
     [[NSColor blackColor] setStroke];
 
     NSRect lastRect;
+    bzero(&lastRect, sizeof(lastRect));
     int index = 0;
     for (NSValue *rectValue in [self rectsForRefsinRect:*refRect])
     {