diff --git a/Cocoa/Document.m b/Cocoa/Document.m
index 7cb0eea..c9205ce 100644
--- a/Cocoa/Document.m
+++ b/Cocoa/Document.m
@@ -334,7 +334,7 @@ static void printImage(GB_gameboy_t *gb, uint32_t *image, uint8_t height,
     NSMutableParagraphStyle *paragraph_style = [[NSMutableParagraphStyle alloc] init];
     [paragraph_style setLineSpacing:2];
     
-    self.mainWindow.backgroundColor = [NSColor blackColor];
+    self.mainWindow.contentView.layer.backgroundColor = [[NSColor blackColor] CGColor];
     
     self.debuggerSideViewInput.font = [NSFont userFixedPitchFontOfSize:12];
     self.debuggerSideViewInput.textColor = [NSColor whiteColor];