diff --git a/src/eodash_catalog/endpoints.py b/src/eodash_catalog/endpoints.py
index 070ec096..3dc9ac53 100644
--- a/src/eodash_catalog/endpoints.py
+++ b/src/eodash_catalog/endpoints.py
@@ -14,6 +14,7 @@
 import pyarrow.parquet as pq
 import requests
 from pystac import Asset, Catalog, Collection, Item, Link, SpatialExtent, Summaries, TemporalExtent
+from pystac.extensions.file import FileExtension
 from pystac_client import Client
 from shapely import wkt
 from shapely.geometry import mapping
@@ -1586,15 +1587,15 @@ def handle_raw_source(
             extents = extract_extent_from_geoparquet(table)
             collection.extent.temporal = extents[0]
             collection.extent.spatial = extents[1]
-            collection.add_asset(
-                "geoparquet",
-                Asset(
-                    href=parquet_source,
-                    media_type="application/vnd.apache.parquet",
-                    title="GeoParquet Items",
-                    roles=["collection-mirror"],
-                ),
+            parquet_asset = Asset(
+                href=parquet_source,
+                media_type="application/vnd.apache.parquet",
+                title="GeoParquet Items",
+                roles=["collection-mirror"],
             )
+            collection.add_asset("geoparquet", parquet_asset)
+            # adding this size explicitly here because github pages gzips the file
+            FileExtension.ext(parquet_asset, add_if_missing=True).size = len(parquet_file.content)
 
     else:
         LOGGER.warn(f"NO datetimes configured for collection: {collection_config['Name']}!")
diff --git a/src/eodash_catalog/utils.py b/src/eodash_catalog/utils.py
index dc78078b..caa04847 100644
--- a/src/eodash_catalog/utils.py
+++ b/src/eodash_catalog/utils.py
@@ -19,6 +19,7 @@
 from owslib.wms import WebMapService
 from owslib.wmts import WebMapTileService
 from pystac import Asset, Catalog, Collection, Item, RelType, SpatialExtent, TemporalExtent
+from pystac.extensions.file import FileExtension
 from pytz import timezone as pytztimezone
 from shapely import geometry as sgeom
 from shapely import wkb
@@ -634,20 +635,21 @@ def save_items(
         table = record_batch_reader.read_all()
         output_path = f"{buildcatpath}/{colpath}"
         os.makedirs(output_path, exist_ok=True)
-        stacgp.arrow.to_parquet(table, f"{output_path}/items.parquet")
+        parquet_path = f"{output_path}/items.parquet"
+        stacgp.arrow.to_parquet(table, parquet_path)
         extents = extract_extent_from_geoparquet(table)
         collection.extent.temporal = extents[0]
         collection.extent.spatial = extents[1]
         # Make sure to also reference the geoparquet as asset
-        collection.add_asset(
-            "geoparquet",
-            Asset(
-                href="./items.parquet",
-                media_type="application/vnd.apache.parquet",
-                title="GeoParquet Items",
-                roles=["collection-mirror"],
-            ),
+        parquet_asset = Asset(
+            href="./items.parquet",
+            media_type="application/vnd.apache.parquet",
+            title="GeoParquet Items",
+            roles=["collection-mirror"],
         )
+        collection.add_asset("geoparquet", parquet_asset)
+        # adding this size explicitly here because github pages gzips the file
+        FileExtension.ext(parquet_asset, add_if_missing=True).size = os.path.getsize(parquet_path)
     else:
         # go over items and add them to the collection
         LOGGER.info(
diff --git a/tests/test_geoparquet.py b/tests/test_geoparquet.py
index b5f9e999..9ef5d69a 100644
--- a/tests/test_geoparquet.py
+++ b/tests/test_geoparquet.py
@@ -51,6 +51,12 @@ def test_geoparquet_geojson_items(catalog_output_folder):
         assert parquet_asset["type"] == "application/vnd.apache.parquet"
         items_path = os.path.join(child_collection_path, parquet_asset["href"].split("/")[-1])
         assert os.path.exists(items_path)
+        # size is advertised so the client does not have to probe the mirror over HTTP
+        assert (
+            "https://stac-extensions.github.io/file/v2.1.0/schema.json"
+            in collection_json["stac_extensions"]
+        )
+        assert parquet_asset["file:size"] == os.path.getsize(items_path)
 
     with open(items_path, "rb") as fp:
         table = pa.parquet.read_table(fp)