diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5c7d20f4f..fbbca9edf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,10 @@ All notable changes to this project will be documented in this file.
 
 - opensearch: Remove the `performance-analyzer` plugin from the OpenSearch image ([#1357]).
 
+### Fixed
+
+- testing-tools: Re-add `pytest` Python package as well as `diffutils` package ([#1388]).
+
 [#1336]: https://github.com/stackabletech/docker-images/pull/1336
 [#1337]: https://github.com/stackabletech/docker-images/pull/1337
 [#1340]: https://github.com/stackabletech/docker-images/pull/1340
@@ -40,6 +44,7 @@ All notable changes to this project will be documented in this file.
 [#1373]: https://github.com/stackabletech/docker-images/pull/1373
 [#1386]: https://github.com/stackabletech/docker-images/pull/1386
 [#1387]: https://github.com/stackabletech/docker-images/pull/1387
+[#1388]: https://github.com/stackabletech/docker-images/pull/1388
 
 ## [25.11.0] - 2025-11-07
 
diff --git a/testing-tools/Dockerfile b/testing-tools/Dockerfile
index d19a4309e..7bb73bf75 100644
--- a/testing-tools/Dockerfile
+++ b/testing-tools/Dockerfile
@@ -63,7 +63,9 @@ microdnf install \
   curl \
   tar \
   zip \
-  unzip
+  unzip \
+  `# Required to do test assertions of files` \
+  diffutils
 
 microdnf clean all
 rm -rf /var/cache/yum
diff --git a/testing-tools/requirements.txt b/testing-tools/requirements.txt
index 3a7636da1..ef48ae2a4 100644
--- a/testing-tools/requirements.txt
+++ b/testing-tools/requirements.txt
@@ -2,6 +2,8 @@
 # Beautiful Soup pulls data out of HTML.
 beautifulsoup4==4.14.2
 requests==2.32.5
+# Needed to run Python tests
+pytest==9.0.2
 
 # Packages that were previously installed as system packages
 certifi==2025.11.12