diff --git a/pym/install/variables/X11.py b/pym/install/variables/X11.py
index 5bb4cf7..dbfc273 100644
--- a/pym/install/variables/X11.py
+++ b/pym/install/variables/X11.py
@@ -416,7 +416,7 @@ class VariableClGrubImageHash(ReadonlyVariable):
     theme_data = "/etc/grub.d/05_theme"
 
     def get_image_md5(self, source):
-        return hashlib.md5(readFile(source)).hexdigest()
+        return hashlib.md5(readFile(source, binary=True)).hexdigest()
 
     def get_config_md5(selfself, source):
         return hashlib.md5(readFileEx(source, grab=True)).hexdigest()