diff --git a/buildbot/master.cfg b/buildbot/master.cfg
index 02d6cfd..f57a176 100644
--- a/buildbot/master.cfg
+++ b/buildbot/master.cfg
@@ -19,14 +19,14 @@ c = BuildmasterConfig = {}
 # worker name and password must be configured on the worker.
 #c['workers'] = [worker.Worker("worker", "work3rP@ss!")]
 c['workers'] = [
-    worker.DockerLatentWorker('f26', 'work3rP@ss!',
-                              docker_host='unix:///var/run/docker.sock',
-                              image='buildbot-worker:26',
-                              hostconfig={'cap_add': ['SYS_ADMIN']}),
     worker.DockerLatentWorker('f27', 'work3rP@ss!',
                               docker_host='unix:///var/run/docker.sock',
                               image='buildbot-worker:27',
                               hostconfig={'cap_add': ['SYS_ADMIN'], 'security_opt': ['apparmor=unconfined']}),
+    worker.DockerLatentWorker('f28', 'work3rP@ss!',
+                              docker_host='unix:///var/run/docker.sock',
+                              image='buildbot-worker:28',
+                              hostconfig={'cap_add': ['SYS_ADMIN'], 'security_opt': ['apparmor=unconfined']}),
 ]
 # 'protocols' contains information about protocols which master will use for
 # communicating with workers. You must define at least 'port' option that workers
@@ -62,12 +62,12 @@ c['schedulers'] = []
 c['schedulers'].append(schedulers.ForceScheduler(
                             name="Force_QGIS",
                             builderNames=["qgis"]))
-c['schedulers'].append(schedulers.ForceScheduler(
-                            name="Force_QGIS_DNF_F26",
-                            builderNames=["qgis_dnf_f26"]))
 c['schedulers'].append(schedulers.ForceScheduler(
                             name="Force_QGIS_DNF_F27",
                             builderNames=["qgis_dnf_f27"]))
+c['schedulers'].append(schedulers.ForceScheduler(
+                            name="Force_QGIS_DNF_F28",
+                            builderNames=["qgis_dnf_f28"]))
 
 ####### BUILDERS
 
@@ -103,11 +103,11 @@ qgis_install_factory.addStep(steps.ShellCommand(command=["/usr/bin/qgis", "--hel
 c['builders'] = []
 c['builders'].append(
     util.BuilderConfig(name="qgis",
-      workernames=["f27"],
+      workernames=["f28"],
       factory=qgis_factory))
 c['builders'].append(
-    util.BuilderConfig(name="qgis_dnf_f26",
-      workernames=["f26"],
+    util.BuilderConfig(name="qgis_dnf_f28",
+      workernames=["f28"],
       factory=qgis_install_factory))
 c['builders'].append(
     util.BuilderConfig(name="qgis_dnf_f27",
diff --git a/docker/Dockerfile.f27 b/docker/Dockerfile.f27
index 3b4fb71..d713634 100644
--- a/docker/Dockerfile.f27
+++ b/docker/Dockerfile.f27
@@ -4,15 +4,15 @@ MAINTAINER Daniele Viganò <daniele@vigano.me>
 
 RUN dnf install -y sudo findutils tar bzip2 git python3-pip mock copr-cli && \
     dnf clean all && \
-    find /var/cache/dnf -type d -delete
+    find /var/cache/dnf -type f -delete
 # Use a Twisted binary wheel to avoid too many dependencies
 RUN pip3 install https://daniele.vigano.me/files/pypi/Twisted-17.9.0-cp36-cp36m-manylinux1_x86_64.whl \
-                 buildbot-worker
+                 buildbot-worker==1.2.0
 
 RUN useradd -u 1000 builder && \
     usermod -a -G mock builder
 
-RUN echo "builder ALL=(ALL) NOPASSWD: /usr/bin/dnf" >> /etc/sudoers
+RUN echo "builder ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
 
 USER builder
 ENV HOME /home/builder
diff --git a/docker/Dockerfile.f26 b/docker/Dockerfile.f28
similarity index 62%
rename from docker/Dockerfile.f26
rename to docker/Dockerfile.f28
index 582c7ad..8be8d63 100644
--- a/docker/Dockerfile.f26
+++ b/docker/Dockerfile.f28
@@ -1,27 +1,27 @@
 # vi:syntax=dockerfile
-FROM registry.fedoraproject.org/fedora:26
+FROM registry.fedoraproject.org/fedora:28
 MAINTAINER Daniele Viganò <daniele@vigano.me>
 
 RUN dnf install -y sudo findutils tar bzip2 git python3-pip mock copr-cli && \
     dnf clean all && \
-    find /var/cache/dnf -type d -delete
+    find /var/cache/dnf -type f -delete
 # Use a Twisted binary wheel to avoid too many dependencies
 RUN pip3 install https://daniele.vigano.me/files/pypi/Twisted-17.9.0-cp36-cp36m-manylinux1_x86_64.whl \
-                 buildbot-worker
+                 buildbot-worker==1.2.0
 
 RUN useradd -u 1000 builder && \
     usermod -a -G mock builder
 
-RUN echo "builder ALL=(ALL) NOPASSWD: /usr/bin/dnf" >> /etc/sudoers
+RUN echo "builder ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
 
 USER builder
 ENV HOME /home/builder
 WORKDIR ${HOME}
 
-RUN buildbot-worker create-worker $HOME 172.17.0.1 f26 work3rP@ss! && \
+RUN buildbot-worker create-worker $HOME 172.17.0.1 f28 work3rP@ss! && \
     echo "Daniele Viganò <daniel@vigano.me>" > info/admin && \
-    echo "Docker running Fedora 26 (x86_64)" > info/host
+    echo "Docker running Fedora 28 (x86_64)" > info/host
 
 COPY copr $HOME/.config/copr
-ENTRYPOINT ["/usr/bin/buildbot-worker"]
+ENTRYPOINT ["/usr/local/bin/buildbot-worker"]
 CMD ["start", "--nodaemon"]