diff --git a/src/osx/core/bitmap.cpp b/src/osx/core/bitmap.cpp
index 916a06b6ca..5d954386fa 100644
--- a/src/osx/core/bitmap.cpp
+++ b/src/osx/core/bitmap.cpp
@@ -336,7 +336,7 @@ int wxBitmapRefData::GetBytesPerRow() const
 
 bool wxBitmapRefData::HasAlpha() const
 {
-    wxCHECK_MSG( IsOk() , 0 , "Invalid Bitmap");
+    wxCHECK_MSG( IsOk() , false , "Invalid Bitmap");
 
     if ( m_hBitmap )
     {