diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index c9dc230..c62ea5b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -101,15 +101,21 @@ jobs:
               exit 0
             fi
 
-            # Also check all commits in the PR for [build]
+            # Set up PR refs and fetch base branch to ensure we have the commits
             BASE_SHA="${{ github.event.pull_request.base.sha }}"
             HEAD_SHA="${{ github.event.pull_request.head.sha }}"
-            COMMIT_MSGS=$(git fetch origin "$BASE_SHA" "$HEAD_SHA" && git log --format=%B "${BASE_SHA}..${HEAD_SHA}" || echo "")
+            git fetch origin "${{ github.event.pull_request.base.ref }}" --quiet || true
+
+            # Check all commits in the PR for [build]
+            COMMIT_MSGS=$(git log --format=%B "${BASE_SHA}..${HEAD_SHA}" 2>/dev/null || echo "")
             if echo "$COMMIT_MSGS" | grep -q "\[build\]"; then
               echo "should_build=true" >> "$GITHUB_OUTPUT"
               echo "Running build because a commit in the PR contains [build]"
               exit 0
             fi
+
+            # Check which files changed in the PR
+            CHANGED_FILES=$(git diff --name-only "${BASE_SHA}" "${HEAD_SHA}" 2>/dev/null || echo "")
           else
             # For pushes, check if the head commit message contains [build]
             if [[ "${{ contains(github.event.head_commit.message, '[build]') }}" == "true" ]]; then
@@ -117,14 +123,7 @@ jobs:
               echo "Running build because commit message contains [build]"
               exit 0
             fi
-          fi
 
-          # For PRs, compare the PR base with the head
-          if [[ "${{ github.event_name }}" == "pull_request" ]]; then
-            BASE_SHA="${{ github.event.pull_request.base.sha }}"
-            HEAD_SHA="${{ github.event.pull_request.head.sha }}"
-            CHANGED_FILES=$(git fetch origin "$BASE_SHA" "$HEAD_SHA" && git diff --name-only "${BASE_SHA}" "${HEAD_SHA}" || echo "")
-          else
             # For pushes, use the before/after SHAs or fallback to comparing with parent
             BEFORE_SHA="${{ github.event.before }}"
             AFTER_SHA="${{ github.event.after }}"
diff --git a/src/hyperscan/extension.c b/src/hyperscan/extension.c
index cb61de8..f34e497 100644
--- a/src/hyperscan/extension.c
+++ b/src/hyperscan/extension.c
@@ -717,12 +717,12 @@ static PyObject *Database_scan(Database *self, PyObject *args, PyObject *kwds)
     char **data;
     PyObject *fast_seq;
     Py_ssize_t num_buffers;
-    Py_ssize_t *lengths;
+    uint32_t *lengths;
 
     fast_seq = PySequence_Fast(odata, "expected a sequence of buffers");
     num_buffers = PySequence_Fast_GET_SIZE(fast_seq);
     data = PyMem_RawMalloc(num_buffers * sizeof(char *));
-    lengths = PyMem_RawMalloc(num_buffers * sizeof(Py_ssize_t));
+    lengths = PyMem_RawMalloc(num_buffers * sizeof(uint32_t));
 
     for (uint32_t i = 0; i < num_buffers; i++) {
       PyObject *o = PySequence_Fast_GET_ITEM(fast_seq, i);
@@ -735,7 +735,7 @@ static PyObject *Database_scan(Database *self, PyObject *args, PyObject *kwds)
       Py_buffer view;
       if (PyObject_GetBuffer(o, &view, PyBUF_SIMPLE) != -1) {
         data[i] = (char *)view.buf;
-        lengths[i] = view.len;
+        lengths[i] = (uint32_t)view.len;
       } else {
         PyErr_SetString(PyExc_BufferError, "failed to get buffer");
         break;
@@ -761,7 +761,7 @@ static PyObject *Database_scan(Database *self, PyObject *args, PyObject *kwds)
     hs_err = hs_scan_vector(
       self->hs_db,
       (const char *const *)data,
-      (const uint32_t *)lengths,
+      lengths,
       num_buffers,
       flags,
       oscratch == Py_None ? ((Scratch *)self->scratch)->hs_scratch
diff --git a/tests/test_hyperscan.py b/tests/test_hyperscan.py
index f5a519a..e9d5ea5 100644
--- a/tests/test_hyperscan.py
+++ b/tests/test_hyperscan.py
@@ -120,19 +120,28 @@ def test_stream_scan(database_stream, mocker):
 
 
 def test_vectored_scan(database_vector, mocker):
+    """Test vectored scanning across multiple buffers.
+
+    Regression test for issue #202: vectored mode was missing matches
+    due to Py_ssize_t to uint32_t type aliasing bug on 64-bit systems.
+    """
     callback = mocker.Mock(return_value=None)
 
     buffers = [
-        bytearray(b"xxxfooxxx"),
-        bytearray(b"xxfoxbarx"),
-        bytearray(b"barxxxxxx"),
+        bytearray(b"xxxfooxxx"),  # 9 bytes, offsets 0-8
+        bytearray(b"xxfoxbarx"),  # 9 bytes, offsets 9-17
+        bytearray(b"barxxxxxx"),  # 9 bytes, offsets 18-26
     ]
     database_vector.scan(buffers, match_event_handler=callback)
     callback.assert_has_calls(
         [
-            mocker.call(0, 0, 5, 0, None),
-            mocker.call(0, 0, 6, 0, None),
-            mocker.call(2, 9, 12, 0, None),
+            # Pattern 0 (fo+): matches in buffer 0 and buffer 1
+            mocker.call(0, 0, 5, 0, None),   # 'fo' at positions 3-4
+            mocker.call(0, 0, 6, 0, None),   # 'foo' at positions 3-5
+            mocker.call(0, 0, 13, 0, None),  # 'fo' in buffer 1 at pos 11-12
+            # Pattern 2 (BAR): matches in buffer 1 and buffer 2
+            mocker.call(2, 14, 17, 0, None),  # 'bar' in buffer 1
+            mocker.call(2, 18, 21, 0, None),  # 'bar' in buffer 2
         ],
         any_order=True,
     )