diff --git a/compliance_checker/protocols/zarr.py b/compliance_checker/protocols/zarr.py
index 8600f22c..f111624c 100644
--- a/compliance_checker/protocols/zarr.py
+++ b/compliance_checker/protocols/zarr.py
@@ -10,7 +10,8 @@
 
 
 def is_zarr(url):
-    """ """
+    """Check if a URL is a zarr dataset."""
+    url = str(url)
 
     if netcdf.is_netcdf(url):
         return False