diff --git a/widget/cocoa/nsChildView.mm b/widget/cocoa/nsChildView.mm
index cd0cd80a0019..29df82946cf2 100644
--- a/widget/cocoa/nsChildView.mm
+++ b/widget/cocoa/nsChildView.mm
@@ -3397,7 +3397,7 @@ NSEvent* gLastDragMouseDownEvent = nil;
 
 // This is the analog of nsChildView::MaybeDrawRoundedCorners for CGContexts.
 // We only need to mask the top corners here because Cocoa does the masking
-// for the window's bottom corners automatically (starting with 10.7).
+// for the window's bottom corners automatically.
 - (void)maskTopCornersInContext:(CGContextRef)aContext {
   CGFloat radius = [self cornerRadius];
   int32_t devPixelCornerRadius = mGeckoChild->CocoaPointsToDevPixels(radius);
diff --git a/widget/cocoa/nsCocoaWindow.h b/widget/cocoa/nsCocoaWindow.h
index ad4327b1acc6..d6683a3072b0 100644
--- a/widget/cocoa/nsCocoaWindow.h
+++ b/widget/cocoa/nsCocoaWindow.h
@@ -99,11 +99,6 @@ typedef struct _nsCocoaWindowList {
 // original value.
 - (void)_setWindowNumber:(NSInteger)aNumber;
 
-// If we set the window's stylemask to be textured, the corners on the bottom of
-// the window are rounded by default. We use this private method to make
-// the corners square again, a la Safari. Starting with 10.7, all windows have
-// rounded bottom corners, so this call doesn't have any effect there.
-- (void)setBottomCornerRounded:(BOOL)rounded;
 - (BOOL)bottomCornerRounded;
 
 // Present in the same form on OS X since at least OS X 10.5.
diff --git a/widget/cocoa/nsCocoaWindow.mm b/widget/cocoa/nsCocoaWindow.mm
index 4a087860a69f..a0f5e09c1586 100644
--- a/widget/cocoa/nsCocoaWindow.mm
+++ b/widget/cocoa/nsCocoaWindow.mm
@@ -3170,11 +3170,6 @@ static const NSString* kStateCollectionBehavior = @"collectionBehavior";
     mSheetAttachmentPosition = aContentRect.size.height;
     mWindowButtonsRect = NSZeroRect;
     mFullScreenButtonRect = NSZeroRect;
-
-    // setBottomCornerRounded: is a private API call, so we check to make sure
-    // we respond to it just in case.
-    if ([self respondsToSelector:@selector(setBottomCornerRounded:)])
-      [self setBottomCornerRounded:YES];
   }
   return self;