diff --git a/GUI/ImagePreview.cs b/GUI/ImagePreview.cs
index 0c5b227a..43ddf683 100644
--- a/GUI/ImagePreview.cs
+++ b/GUI/ImagePreview.cs
@@ -271,7 +271,7 @@ namespace GARbro.GUI
                     ImageCanvas.Source = bitmap;
                     ApplyDownScaleSetting();
                     SetStatusText (string.Format (guiStrings.MsgImageSize, bitmap.PixelWidth,
-                                                  bitmap.PixelHeight, bitmap.Format.BitsPerPixel, format.Tag));
+                                                  bitmap.PixelHeight, bitmap.Format.BitsPerPixel, format?.Tag ?? "?"));
                 }
             });
         }