diff --git a/widget/src/cocoa/nsCocoaWindow.h b/widget/src/cocoa/nsCocoaWindow.h
index c12474ebc2c9..f7b6a0892df0 100644
--- a/widget/src/cocoa/nsCocoaWindow.h
+++ b/widget/src/cocoa/nsCocoaWindow.h
@@ -66,7 +66,7 @@ typedef struct _nsCocoaWindowList {
 // (and put it back in the "window cache").  One way to do this, which Apple
 // often uses, is to set the "window number" to '-1' and then back to its
 // original value.
-- (void)_setWindowNumber:(int)aNumber;
+- (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
diff --git a/widget/src/cocoa/nsCocoaWindow.mm b/widget/src/cocoa/nsCocoaWindow.mm
index 73f4bf3833e8..33696c435c97 100644
--- a/widget/src/cocoa/nsCocoaWindow.mm
+++ b/widget/src/cocoa/nsCocoaWindow.mm
@@ -629,7 +629,7 @@ NS_IMETHODIMP nsCocoaWindow::Show(PRBool bState)
       // -- see below).  Setting the window number to -1 and then back to its
       // original value seems to accomplish this.  The idea was "borrowed"
       // from the Java Embedding Plugin.
-      int windowNumber = [mWindow windowNumber];
+      NSInteger windowNumber = [mWindow windowNumber];
       [mWindow _setWindowNumber:-1];
       [mWindow _setWindowNumber:windowNumber];
       [mWindow setAcceptsMouseMovedEvents:YES];