diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1725c0b7..0354cf10 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,11 +3,12 @@
 ### New Checks
 
 ### Improvements
+* Raised the minimum required PyNWB to `>=4.0` to track the latest PyNWB release. [#708](https://github.com/NeurodataWithoutBorders/nwbinspector/pull/708)
 * Bumped GitHub Actions workflow dependencies (`actions/checkout` v4 -> v6, `actions/setup-python` v5 -> v6, `codecov/codecov-action` v4 -> v5) to migrate off Node.js 20, which GitHub is removing from runners on 2026-09-16. [#702](https://github.com/NeurodataWithoutBorders/nwbinspector/pull/702)
 
 ### Fixes
+* Fixed unit tests that failed at construction time against recent PyNWB and HDMF. [#707](https://github.com/NeurodataWithoutBorders/nwbinspector/pull/707) [#708](https://github.com/NeurodataWithoutBorders/nwbinspector/pull/708)
 * Skipped Ontobee in the documentation external link check, which frequently timed out and caused spurious CI failures. [#709](https://github.com/NeurodataWithoutBorders/nwbinspector/pull/709)
-* Fixed unit tests that failed at construction time against recent PyNWB and HDMF. [#707](https://github.com/NeurodataWithoutBorders/nwbinspector/pull/707)
 * Fixed `run_checks` raising `TypeError` when a `progress_bar_class` was passed without `progress_bar_options`; the keyword arguments are now coalesced to an empty dict before being forwarded to the progress-bar constructor. [#701](https://github.com/NeurodataWithoutBorders/nwbinspector/pull/701)
 
 # v0.7.2 (May 19, 2026)
diff --git a/pyproject.toml b/pyproject.toml
index 3985d443..63350a01 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -33,7 +33,7 @@ classifiers = [
 ]
 requires-python = ">=3.10"
 dependencies = [
-    "pynwb>=3.1",   # NWB Inspector should always be used with most recent minor versions of PyNWB
+    "pynwb>=4.0",   # NWB Inspector should always be used with most recent minor versions of PyNWB
     "fsspec",
     "requests",
     "aiohttp",
diff --git a/tests/unit_tests/test_image_series.py b/tests/unit_tests/test_image_series.py
index ef967cb9..92673dce 100644
--- a/tests/unit_tests/test_image_series.py
+++ b/tests/unit_tests/test_image_series.py
@@ -58,6 +58,7 @@ def test_check_image_series_external_file_valid_bytestring_pass(self):
             rate=1.0,
             external_file=[bytes("/".join([".", good_external_path.name]), "utf-8")],
             format="external",
+            num_samples=1,
         )
         assert check_image_series_external_file_relative(image_series=image_series) is None