diff --git a/CHANGES.md b/CHANGES.md
index e339b0e..66031dd 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,8 @@
 
 - Fix Docker compose file, so example data can be loaded into database (author @zstatmanweil, https://github.com/stac-utils/stac-fastapi-pgstac/pull/142)
 
+- Fix `filter` extension implementation in `CoreCrudClient`
+
 ## [3.0.0] - 2024-08-02
 
 - Enable filter extension for `GET /items` requests and add `Queryables` links in `/collections` and `/collections/{collection_id}` responses ([#89](https://github.com/stac-utils/stac-fastapi-pgstac/pull/89))
diff --git a/docker-compose.yml b/docker-compose.yml
index d39942e..ec1080a 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -1,4 +1,3 @@
-version: '3'
 services:
   app:
     container_name: stac-fastapi-pgstac
@@ -67,8 +66,8 @@ services:
       - ./scripts:/app/scripts
     command: >
       /bin/sh -c "
-        ./scripts/wait-for-it.sh -t 60 app:8082 && 
-        python -m pip install requests && 
+        ./scripts/wait-for-it.sh -t 60 app:8082 &&
+        python -m pip install requests &&
         python /app/scripts/ingest_joplin.py http://app:8082
         "
     depends_on:
diff --git a/stac_fastapi/pgstac/core.py b/stac_fastapi/pgstac/core.py
index 648d42a..7a39b50 100644
--- a/stac_fastapi/pgstac/core.py
+++ b/stac_fastapi/pgstac/core.py
@@ -310,11 +310,14 @@ async def item_collection(
 
         if self.extension_is_enabled("FilterExtension"):
             filter_lang = kwargs.get("filter_lang", None)
-            filter = kwargs.get("filter", None)
-            if filter is not None and filter_lang == "cql2-text":
-                ast = parse_cql2_text(filter.strip())
-                base_args["filter"] = orjson.loads(to_cql2(ast))
-                base_args["filter-lang"] = "cql2-json"
+            filter_query = kwargs.get("filter", None)
+            if filter_query:
+                if filter_lang == "cql2-text":
+                    filter_query = to_cql2(parse_cql2_text(filter_query))
+                    filter_lang = "cql2-json"
+
+                base_args["filter"] = orjson.loads(filter_query)
+                base_args["filter-lang"] = filter_lang
 
         clean = {}
         for k, v in base_args.items():
@@ -420,9 +423,11 @@ async def get_search(  # noqa: C901
 
         if filter:
             if filter_lang == "cql2-text":
-                ast = parse_cql2_text(filter)
-                base_args["filter"] = orjson.loads(to_cql2(ast))
-                base_args["filter-lang"] = "cql2-json"
+                filter = to_cql2(parse_cql2_text(filter))
+                filter_lang = "cql2-json"
+
+            base_args["filter"] = orjson.loads(filter)
+            base_args["filter-lang"] = filter_lang
 
         if datetime:
             base_args["datetime"] = format_datetime_range(datetime)
diff --git a/tests/resources/test_item.py b/tests/resources/test_item.py
index 7964266..a077116 100644
--- a/tests/resources/test_item.py
+++ b/tests/resources/test_item.py
@@ -1540,3 +1540,116 @@ async def test_get_collection_items_duplicate_forwarded_headers(
     )
     for link in resp.json()["features"][0]["links"]:
         assert link["href"].startswith("https://test:1234/")
+
+
+async def test_get_filter_extension(app_client, load_test_data, load_test_collection):
+    """Test GET with Filter extension"""
+    test_item = load_test_data("test_item.json")
+    collection_id = test_item["collection"]
+    ids = []
+
+    # Ingest 5 items
+    for _ in range(5):
+        uid = str(uuid.uuid4())
+        test_item["id"] = uid
+        resp = await app_client.post(
+            f"/collections/{collection_id}/items", json=test_item
+        )
+        assert resp.status_code == 201
+        ids.append(uid)
+
+    search_id = ids[2]
+
+    # SEARCH
+    # CQL2-JSON
+    resp = await app_client.get(
+        "/search",
+        params={
+            "filter-lang": "cql2-json",
+            "filter": json.dumps({"op": "in", "args": [{"property": "id"}, [search_id]]}),
+        },
+    )
+    assert resp.status_code == 200
+    fc = resp.json()
+    assert len(fc["features"]) == 1
+    assert fc["features"][0]["id"] == search_id
+
+    # CQL-JSON
+    resp = await app_client.get(
+        "/search",
+        params={
+            "filter-lang": "cql-json",
+            "filter": json.dumps(
+                {
+                    "eq": [
+                        {"property": "id"},
+                        search_id,
+                    ],
+                },
+            ),
+        },
+    )
+    assert resp.status_code == 200
+    fc = resp.json()
+    assert len(fc["features"]) == 1
+    assert fc["features"][0]["id"] == search_id
+
+    # CQL2-TEXT
+    resp = await app_client.get(
+        "/search",
+        params={
+            "filter-lang": "cql2-text",
+            "filter": f"id='{search_id}'",
+        },
+    )
+    assert resp.status_code == 200
+    fc = resp.json()
+    assert len(fc["features"]) == 1
+    assert fc["features"][0]["id"] == search_id
+
+    # ITEM COLLECTION
+    # CQL2-JSON
+    resp = await app_client.get(
+        f"/collections/{collection_id}/items",
+        params={
+            "filter-lang": "cql2-json",
+            "filter": json.dumps({"op": "in", "args": [{"property": "id"}, [search_id]]}),
+        },
+    )
+    assert resp.status_code == 200
+    fc = resp.json()
+    assert len(fc["features"]) == 1
+    assert fc["features"][0]["id"] == search_id
+
+    # CQL-JSON
+    resp = await app_client.get(
+        f"/collections/{collection_id}/items",
+        params={
+            "filter-lang": "cql-json",
+            "filter": json.dumps(
+                {
+                    "eq": [
+                        {"property": "id"},
+                        search_id,
+                    ],
+                },
+            ),
+        },
+    )
+    assert resp.status_code == 200
+    fc = resp.json()
+    assert len(fc["features"]) == 1
+    assert fc["features"][0]["id"] == search_id
+
+    # CQL2-TEXT
+    resp = await app_client.get(
+        f"/collections/{collection_id}/items",
+        params={
+            "filter-lang": "cql2-text",
+            "filter": f"id='{search_id}'",
+        },
+    )
+    assert resp.status_code == 200
+    fc = resp.json()
+    assert len(fc["features"]) == 1
+    assert fc["features"][0]["id"] == search_id