diff --git a/kindlecomicconverter/image.py b/kindlecomicconverter/image.py
index 5f96699..0c28226 100755
--- a/kindlecomicconverter/image.py
+++ b/kindlecomicconverter/image.py
@@ -423,6 +423,10 @@ class ComicPage:
         bbox = get_bbox_crop_margin_page_number(self.image, power, self.fill)
         
         if bbox:
+            w, h = self.image.size
+            left, upper, right, lower = bbox
+            # don't crop more than 10% of image
+            bbox = (min(0.1*w, left), min(0.1*h, upper), max(0.9*w, right), max(0.9*h, lower))
             self.maybeCrop(bbox, minimum)
 
     def cropMargin(self, power, minimum):