diff --git a/HACKING b/HACKING
index 3b51ed1..2a8df80 100644
--- a/HACKING
+++ b/HACKING
@@ -32,9 +32,8 @@ Tests
 
 To run all tests on all supported platforms:
 
-    yum -y install docker-io
-    systemctl start docker.service
-    systemctl enable docker.service
+    yum -y install docker
+    systemctl enable --now docker.service
     usermod -aG docker <your-username>
 
 Log out and log in to refresh your secondary group.
@@ -55,16 +54,13 @@ Expected output resembles:
     -snip copious output-
     =====================
     Summary
-    /tmp/titotest-centos-5.9-python.out     : OK (SKIP=1)
-    /tmp/titotest-centos-6.4-python.out     : OK (SKIP=1)
-    /tmp/titotest-fedora-20-python.out      : OK
-    /tmp/titotest-fedora-20-python3.out     : OK
+    /tmp/titotest-centos-6-python.out     : OK (SKIP=1)
+    /tmp/titotest-fedora-25-python3.out     : OK
 
 You can then review the output, such as:
 
     $ grep SKIP: /tmp/titotest-*.out
-    /tmp/titotest-centos-5.9-python.out:... SKIP: git-annex is not available in epel-5
-    /tmp/titotest-centos-6.4-python.out:... SKIP: git-annex '3.20120522 ' is too old
+    /tmp/titotest-centos-6-python.out:... SKIP: git-annex '3.20120522 ' is too old
 
 After you run the test harness the first time,
 you can optionally create and enter a container like so:
@@ -75,9 +71,9 @@ you can optionally create and enter a container like so:
                  |   |  .--- tty
                  |   |  |  .---- mount current workdir into container
                  |   |  |  |                    .---- name of image
-                 |   |  |  |                    |                   .-- get a shell
-                 |   |  |  |                    |                   |
-    docker run --rm -i -t -v $PWD:/home/sandbox titotest-centos-5.9 /bin/bash
+                 |   |  |  |                    |                 .-- get a shell
+                 |   |  |  |                    |                 |
+    docker run --rm -i -t -v $PWD:/home/sandbox titotest-centos-6 /bin/bash
 
 
 Note about the sandbox: By default, the docker container is a
diff --git a/hacking/runtests.sh b/hacking/runtests.sh
index f08e495..1765d00 100755
--- a/hacking/runtests.sh
+++ b/hacking/runtests.sh
@@ -10,9 +10,8 @@
 #
 # To run all tests on all supported platforms:
 #
-#     yum -y install docker-io
-#     systemctl start docker.service
-#     systemctl enable docker.service
+#     yum -y install docker
+#     systemctl enable --now docker.service
 #     usermod -aG docker <your-username>
 #
 # Log out and log in to refresh your secondary group.
@@ -39,16 +38,13 @@
 #     -snip copious output-
 #     =====================
 #     Summary
-#     /tmp/titotest-centos-5.9-python.out     : OK (SKIP=1)
-#     /tmp/titotest-centos-6.4-python.out     : OK (SKIP=1)
-#     /tmp/titotest-fedora-20-python.out      : OK
-#     /tmp/titotest-fedora-20-python3.out     : OK
+#     /tmp/titotest-centos-6-python.out     : OK (SKIP=1)
+#     /tmp/titotest-fedora-25-python3.out     : OK
 #
 # You can then review the output, such as:
 #
 #     $ grep SKIP: /tmp/titotest-*.out
-#     /tmp/titotest-centos-5.9-python.out:... SKIP: git-annex is not available in epel-5
-#     /tmp/titotest-centos-6.4-python.out:... SKIP: git-annex '3.20120522 ' is too old
+#     /tmp/titotest-centos-6-python.out:... SKIP: git-annex '3.20120522 ' is too old
 #
 # After you run the test harness the first time,
 # you can optionally enter a container like so:
@@ -59,12 +55,9 @@
 #                  |   |  .--- tty
 #                  |   |  |  .---- mount current workdir into container
 #                  |   |  |  |                    .---- name of image
-#                  |   |  |  |                    |                   .-- get a shell
-#                  |   |  |  |                    |                   |
-#     docker run --rm -i -t -v $PWD:/home/sandbox titotest-centos-5.9 /bin/bash
-
-# Pip no longer supported here, can't install mock libraries:
-#titotest-centos-5.9
+#                  |   |  |  |                    |                 .-- get a shell
+#                  |   |  |  |                    |                 |
+#     docker run --rm -i -t -v $PWD:/home/sandbox titotest-centos-6 /bin/bash
 
 readonly default_python2_distros=(
     centos-6
diff --git a/hacking/titotest-centos-5/Dockerfile b/hacking/titotest-centos-5/Dockerfile
deleted file mode 100644
index c355532..0000000
--- a/hacking/titotest-centos-5/Dockerfile
+++ /dev/null
@@ -1,33 +0,0 @@
-# https://index.docker.io/_/centos/
-FROM centos:5
-
-# http://jumanjiman.github.io/
-MAINTAINER Paul Morgan <jumanjiman@gmail.com>
-
-# Install dependencies.
-# It would be nice to use yum-builddep, but
-# el5 yum-builddep only works against rpm, not spec file.
-RUN rpm -Uvh http://mirror.es.its.nyu.edu/epel/5/x86_64/epel-release-5-4.noarch.rpm
-RUN yum -y install git rpm-build \
-    python-devel python-nose python-setuptools python-pep8 \
-    python-pip \
-    docbook-style-xsl \
-    rpmdevtools \
-    libxslt asciidoc tar createrepo which python-bugzilla
-
-RUN pip-python install mock --upgrade
-
-# Remove yum metadata.
-RUN yum clean all
-
-RUN useradd sandbox
-
-RUN git config --system user.email "sandbox@example.com"
-RUN git config --system user.name  "sandbox"
-
-USER sandbox
-VOLUME ["/home/sandbox"]
-WORKDIR /home/sandbox
-
-ENV LANG C
-CMD ["/bin/bash"]
diff --git a/hacking/titotest-centos-5/README.md b/hacking/titotest-centos-5/README.md
deleted file mode 120000
index fb50ac9..0000000
--- a/hacking/titotest-centos-5/README.md
+++ /dev/null
@@ -1 +0,0 @@
-../../HACKING
\ No newline at end of file