diff --git a/tools/image-info b/tools/image-info
index 4575b7691..39b5b301a 100755
--- a/tools/image-info
+++ b/tools/image-info
@@ -65,7 +65,7 @@ def read_bootloader_type(device):
         if b"GRUB" in f.read(512):
             return "grub"
         else:
-            raise RuntimeError("unkown bootloader")
+            return "unknown"
 
 
 def read_os_release(tree):