diff --git a/adapters/swebench/verification.py b/adapters/swebench/verification.py
index a5fac66..6f18ef1 100644
--- a/adapters/swebench/verification.py
+++ b/adapters/swebench/verification.py
@@ -35,7 +35,7 @@
   "$(git rev-list --count --all)" \\
   "$(git cat-file --batch-all-objects --batch-check='%(objecttype)' | grep -c '^commit$')" \\
   "$(git tag --no-merged HEAD | wc -l)" \\
-  "$(git log --all --format=%B | grep -cE "#$2([^0-9]|$)")"
+  "$(git log --all ${3:+--since="$3"} --format=%B | grep -cE "#$2([^0-9]|$)")"
 """
 HISTORY_FIELDS = ("in_history", "reachable", "stored", "later_tags", "naming_pull_request")
 
@@ -115,9 +115,12 @@ def built_image(task, workdir):
     return environments[0] if len(environments) == 1 else None
 
 
-def history(image, workdir, pull_request_number):
+def history(image, workdir, pull_request_number, opened_at=""):
     probed = subprocess.run(
-        ["docker", "run", "--rm", "--entrypoint", "/bin/bash", image, "-c", HISTORY_PROBE, "probe", workdir, pull_request_number],
+        [
+            "docker", "run", "--rm", "--entrypoint", "/bin/bash", image,
+            "-c", HISTORY_PROBE, "probe", workdir, pull_request_number, opened_at,
+        ],
         capture_output=True,
         text=True,
         timeout=PROBE_TIMEOUT_SECONDS,
@@ -174,8 +177,9 @@ def verified_task(hbench, task, kept_jobs_directory=None):
     if image is None:
         problems.append("cannot find the image hbench built")
     else:
-        summary["built_history"] = history(image, workdir, pull_request)
-        summary["upstream_history"] = history(metadata["base_image"], workdir, pull_request)
+        opened_at = metadata.get("created_at", "")
+        summary["built_history"] = history(image, workdir, pull_request, opened_at)
+        summary["upstream_history"] = history(metadata["base_image"], workdir, pull_request, opened_at)
         problems += history_problems(summary["built_history"])
     summary["problems"] = problems
     return summary
diff --git a/tests/test_swebench_verification.py b/tests/test_swebench_verification.py
new file mode 100644
index 0000000..dd466d5
--- /dev/null
+++ b/tests/test_swebench_verification.py
@@ -0,0 +1,59 @@
+import os
+import pathlib
+import subprocess
+import tempfile
+import unittest
+
+from adapters.swebench import verification
+
+OPENED_AT = "2022-01-13T18:51:58Z"
+
+
+def commit(repository, message, date):
+    environment = {
+        **os.environ,
+        "GIT_AUTHOR_NAME": "Test",
+        "GIT_AUTHOR_EMAIL": "test@example.com",
+        "GIT_AUTHOR_DATE": date,
+        "GIT_COMMITTER_NAME": "Test",
+        "GIT_COMMITTER_EMAIL": "test@example.com",
+        "GIT_COMMITTER_DATE": date,
+    }
+    subprocess.run(
+        ["git", "-C", str(repository), "commit", "--quiet", "--allow-empty", "-m", message],
+        check=True,
+        env=environment,
+    )
+
+
+def probe(repository, pull_request_number, opened_at):
+    completed = subprocess.run(
+        ["bash", "-c", verification.HISTORY_PROBE, "probe", str(repository), pull_request_number, opened_at],
+        check=True,
+        capture_output=True,
+        text=True,
+    )
+    return dict(zip(verification.HISTORY_FIELDS, (int(value) for value in completed.stdout.split())))
+
+
+class HistoryProbeTest(unittest.TestCase):
+    def setUp(self):
+        self.repository = pathlib.Path(self.enterContext(tempfile.TemporaryDirectory()))
+        subprocess.run(["git", "-C", str(self.repository), "init", "--quiet", "--initial-branch=main"], check=True)
+        commit(self.repository, "Fixed #15315 -- Added the widget argument to modelform_factory.", "2011-08-23T04:08:24Z")
+
+    def test_a_ticket_older_than_the_pull_request_does_not_name_it(self):
+        counts = probe(self.repository, "15315", OPENED_AT)
+        self.assertEqual(counts["naming_pull_request"], 0)
+        self.assertEqual(verification.history_problems(counts), [])
+
+    def test_a_message_since_the_pull_request_was_opened_names_it(self):
+        commit(self.repository, "Fixed #33412 -- Fixed the widget's attrs (#15315).", "2022-01-20T09:00:00Z")
+        self.assertEqual(probe(self.repository, "15315", OPENED_AT)["naming_pull_request"], 1)
+
+    def test_without_an_opening_date_every_message_counts(self):
+        self.assertEqual(probe(self.repository, "15315", "")["naming_pull_request"], 1)
+
+
+if __name__ == "__main__":
+    unittest.main()