diff --git a/playbooks/checkout-original-state/run.yaml b/playbooks/checkout-original-state/run.yaml
new file mode 100644
index 0000000..330adce
--- /dev/null
+++ b/playbooks/checkout-original-state/run.yaml
@@ -0,0 +1,3 @@
+- hosts: all
+  roles:
+    - git-use-previous-commit
diff --git a/playbooks/coverage-diff/generate.yaml b/playbooks/coverage-diff/generate.yaml
new file mode 100644
index 0000000..1541fbf
--- /dev/null
+++ b/playbooks/coverage-diff/generate.yaml
@@ -0,0 +1,3 @@
+- hosts: all
+  roles:
+    - pycobertura-diff
diff --git a/playbooks/coverage-diff/upload.yaml b/playbooks/coverage-diff/upload.yaml
new file mode 100644
index 0000000..f1da47d
--- /dev/null
+++ b/playbooks/coverage-diff/upload.yaml
@@ -0,0 +1,3 @@
+- hosts: all
+  roles:
+    - fetch-coverage-xml
diff --git a/roles/fetch-coverage-xml/tasks/main.yaml b/roles/fetch-coverage-xml/tasks/main.yaml
new file mode 100644
index 0000000..5fade16
--- /dev/null
+++ b/roles/fetch-coverage-xml/tasks/main.yaml
@@ -0,0 +1,21 @@
+---
+- name: Set coverage log path
+  set_fact:
+    log_path: "{{ zuul.executor.log_root }}/"
+  when: log_path is not defined
+
+- name: Collect coverage.xml
+  synchronize:
+    src: "{{ coverage_xml_dir }}/coverage.xml"
+    dest: "{{ log_path }}/coverage.xml"
+    mode: pull
+
+- name: Return site artifact location to Zuul
+  zuul_return:
+    data:
+      zuul:
+        artifacts:
+          - name: "Coverage data"
+            metadata:
+              type: "cobertura_xml"
+            url: "coverage.xml"
diff --git a/roles/git-use-previous-commit/tasks/main.yaml b/roles/git-use-previous-commit/tasks/main.yaml
new file mode 100644
index 0000000..9c371e9
--- /dev/null
+++ b/roles/git-use-previous-commit/tasks/main.yaml
@@ -0,0 +1,7 @@
+- name: Prepare git submodules
+  shell: |
+    echo "{{ item.key }}"
+    git checkout -b "zuul_origin_{{ zuul.branch }}" "origin/{{ zuul.branch }}"
+  args:
+    chdir: "{{ ansible_user_dir }}/{{ item.value.src_dir }}"
+  loop: "{{ lookup('dict', zuul.projects) }}"
diff --git a/roles/pycobertura-diff/tasks/main.yaml b/roles/pycobertura-diff/tasks/main.yaml
new file mode 100644
index 0000000..f86e739
--- /dev/null
+++ b/roles/pycobertura-diff/tasks/main.yaml
@@ -0,0 +1,36 @@
+- name: Ensure pycobertura is available
+  pip:
+    name: pycobertura
+    extra_args: --user
+
+- name: Prepare copy of the new version of sources
+  shell: |
+    set -ex
+    NEW_WORK={{ ansible_user_dir }}/new
+    mkdir "${NEW_WORK}"
+    NEW_SRCDIR=${NEW_WORK}/{{ zuul.project.short_name }}
+    pushd {{ zuul.project.src_dir }}
+    git worktree add "${NEW_SRCDIR}" {{ zuul.branch }}
+    popd
+
+- name: Retrieve coverage from parent jobs
+  get_url:
+    url: "{{ item.url }}"
+    dest: "{{ ansible_user_dir }}/new/coverage.xml"
+  when:
+    - item.metadata is defined
+    - item.metadata.type is defined
+    - item.metadata.type == "cobertura_xml"
+  loop: "{{ zuul.artifacts }}"
+
+- name: Generate pycobertura report
+  shell: |
+    set -ex
+    PATH=${PATH}:~/.local/bin
+    pycobertura show --format html --output "{{ ansible_user_dir }}/zuul-output/logs/coverage.html" \
+      --source "{{ ansible_user_dir }}/new/{{ zuul.project.short_name }}" "{{ ansible_user_dir }}/new/coverage.xml"
+    pycobertura diff --format html --output "{{ ansible_user_dir }}/zuul-output/logs/coverage-diff.html" \
+      --source1 "{{ zuul.project.src_dir }}" "{{ coverage_xml_dir }}/coverage.xml" \
+      --source2 "{{ ansible_user_dir }}/new/{{ zuul.project.short_name }}" "{{ ansible_user_dir }}/new/coverage.xml"
+    sed -e 's;^  </body>$;    <p>Show <a href="coverage.html">final coverage</a> only</p>\n  </body>;' \
+      -i "{{ ansible_user_dir }}/zuul-output/logs/coverage-diff.html"
diff --git a/zuul.yaml b/zuul.yaml
index eaa0126..c4b6a8d 100644
--- a/zuul.yaml
+++ b/zuul.yaml
@@ -27,8 +27,24 @@
     description: |
       Build on Fedora 29 with GCC.
     parent: run-ci-build-sh
+    post-run: playbooks/coverage-diff/upload.yaml
     vars:
       perform_extra_work: true
+      coverage_xml_dir: "{{ ansible_user_dir }}/build"
+
+- job:
+    name: f29-gcc-cover-diff
+    description: |
+      Compare difference in coverage as introduced by this change.
+    parent: run-ci-build-sh
+    pre-run: playbooks/checkout-original-state/run.yaml
+    run:
+      - playbooks/run-test-command/run.yaml
+      - playbooks/coverage-diff/generate.yaml
+    success-url: coverage-diff.html
+    failure-url: coverage-diff.html
+    vars:
+      coverage_xml_dir: "{{ ansible_user_dir }}/build"
 
 - job:
     name: f29-gcc-asan