diff --git a/kernel_patches_daemon/patchwork.py b/kernel_patches_daemon/patchwork.py
index d49c05d..f648ad4 100644
--- a/kernel_patches_daemon/patchwork.py
+++ b/kernel_patches_daemon/patchwork.py
@@ -504,7 +504,7 @@ def __init__(
         server: str,
         search_patterns: List[Dict[str, Any]],
         auth_token: Optional[str] = None,
-        lookback_in_days: int = 7,
+        lookback_in_days: int = -1,
         api_version: str = "1.2",
         http_retries: int = DEFAULT_HTTP_RETRIES,
     ) -> None:
@@ -513,7 +513,9 @@ def __init__(
         if not auth_token:
             logger.warning("Patchwork client runs in read-only mode")
         self.search_patterns = search_patterns
-        self.since = self.format_since(lookback_in_days)
+        self.since = (
+            self.format_since(lookback_in_days) if lookback_in_days > 0 else None
+        )
         # member variable initializations
         self.known_series: Dict[int, Series] = {}
         self.known_subjects: Dict[str, Subject] = {}
@@ -716,17 +718,20 @@ async def get_relevant_subjects(self) -> Sequence[Subject]:
         for pattern in self.search_patterns:
             patch_filters = MultiDict(
                 [
-                    ("since", self.since),
                     ("archived", str(False)),
                     *[("state", val) for val in RELEVANT_STATES.values()],
                 ]
             )
+            if self.since is not None:
+                patch_filters.add("since", self.since)
             patch_filters.update({k: str(v) for k, v in pattern.items()})
             logger.info(
                 f"Searching for Patchwork patches that match the criteria: {patch_filters}"
             )
             all_patches = await self.__get_objects_recursive(
-                "patches", params=patch_filters
+                "patches",
+                # pyre-ignore
+                params=patch_filters,
             )
 
             series_ids = set()
diff --git a/tests/common/patchwork_mock.py b/tests/common/patchwork_mock.py
index 578b67a..6889c7e 100644
--- a/tests/common/patchwork_mock.py
+++ b/tests/common/patchwork_mock.py
@@ -37,13 +37,18 @@ def __init__(self, *args: Any, **kwargs: Any) -> None:
         super().__init__(*args, **kwargs)
 
 
-def get_default_pw_client() -> PatchworkMock:
-    return PatchworkMock(
-        server="127.0.0.1",
-        api_version="1.1",
-        search_patterns=[{"archived": False, "project": PROJECT, "delegate": DELEGATE}],
-        auth_token="mocktoken",
-    )
+def get_default_pw_client(**kwargs) -> PatchworkMock:
+    default_params = {
+        "server": "127.0.0.1",
+        "api_version": "1.1",
+        "search_patterns": [
+            {"archived": False, "project": PROJECT, "delegate": DELEGATE}
+        ],
+        "auth_token": "mocktoken",
+        "lookback_in_days": 7,
+    }
+    default_params.update(kwargs)
+    return PatchworkMock(**default_params)
 
 
 def init_pw_responses(m: aioresponses, data: Dict[str, Any]) -> None:
diff --git a/tests/test_patchwork.py b/tests/test_patchwork.py
index 4480142..f876536 100644
--- a/tests/test_patchwork.py
+++ b/tests/test_patchwork.py
@@ -11,7 +11,7 @@
 import re
 import unittest
 from dataclasses import dataclass
-from typing import Any, Dict, List, Optional, Set, Union
+from typing import Any, Callable, Dict, List, Optional, Set, Union
 
 from aioresponses import aioresponses
 
@@ -262,6 +262,30 @@ class TestCase:
                     case.expected,
                 )
 
+    async def _test_lookback(
+        self, m: aioresponses, lookback: int, assert_func: Callable[[str], None]
+    ) -> None:
+        self._pw = get_default_pw_client(lookback_in_days=lookback)
+        m.get(re.compile(r"^.*$"), status=200, body=b"[]")
+        await self._pw.get_relevant_subjects()
+        for request in m.requests.keys():
+            url = str(request[1])
+            assert_func(url)
+
+    @aioresponses()
+    async def test_get_objects_with_lookback(self, m: aioresponses) -> None:
+        """
+        If lookback is > 0, the 'since' query parameter must be present in the requests.
+        """
+        await self._test_lookback(m, 7, lambda url: self.assertIn("since=", url))
+
+    @aioresponses()
+    async def test_get_objects_no_lookback(self, m: aioresponses) -> None:
+        """
+        If lookback is <= 0, the 'since' query parameter must not be present in the requests.
+        """
+        await self._test_lookback(m, -1, lambda url: self.assertNotIn("since=", url))
+
 
 class TestSeries(PatchworkTestCase):
     @aioresponses()