diff --git a/widget/src/cocoa/nsCocoaWindow.mm b/widget/src/cocoa/nsCocoaWindow.mm
index 9cb0afd70fa3b..efc433633ab74 100644
--- a/widget/src/cocoa/nsCocoaWindow.mm
+++ b/widget/src/cocoa/nsCocoaWindow.mm
@@ -1736,12 +1736,6 @@ - (id)initWithContentRect:(NSRect)aContentRect styleMask:(unsigned int)aStyle ba
     // we respond to it just in case.
     if ([self respondsToSelector:@selector(setBottomCornerRounded:)])
       [self setBottomCornerRounded:NO];
-
-    // This method only exists on Leopard.
-    if ([self respondsToSelector:@selector(setAutorecalculatesContentBorderThickness:forEdge:)]) {
-      [self setAutorecalculatesContentBorderThickness:NO forEdge:NSMaxYEdge];
-      [self setContentBorderThickness:0.0f forEdge:NSMaxYEdge];
-    }
   }
   return self;
 
@@ -1803,8 +1797,6 @@ - (void)setUnifiedToolbarHeight:(float)aToolbarHeight
   if (mUnifiedToolbarHeight == aToolbarHeight)
     return;
   mUnifiedToolbarHeight = aToolbarHeight;
-  if ([self respondsToSelector:@selector(setContentBorderThickness:forEdge:)])
-    [self setContentBorderThickness:aToolbarHeight forEdge:NSMaxYEdge];
   [self redrawTitlebar];
 }