diff --git a/.travis.yml b/.travis.yml
index 4f15d19d8..50bfc3294 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -51,5 +51,5 @@ after_success:
 
     # Coverage and quality reports on just the latest diff.
     # (Installation is very slow on Py3, so just do it for Py2.)
-  - if [ ${TRAVIS_PYTHON_VERSION:0:1} == "2" ]; then git fetch origin master:refs/remotes/origin/master; fi
-  - if [ ${TRAVIS_PYTHON_VERSION:0:1} == "2" ]; then Scripts/diffcover.sh; fi
+  - if [ ${TRAVIS_PYTHON_VERSION:0:1} == "2" ]; then Scripts/diffcover-install.sh; fi
+  - if [ ${TRAVIS_PYTHON_VERSION:0:1} == "2" ]; then Scripts/diffcover-report.sh; fi
diff --git a/Scripts/diffcover-install.sh b/Scripts/diffcover-install.sh
new file mode 100755
index 000000000..93e06efe3
--- /dev/null
+++ b/Scripts/diffcover-install.sh
@@ -0,0 +1,7 @@
+# Fetch the remote master branch before running diff-cover on Travis CI.
+# https://github.com/edx/diff-cover#troubleshooting
+git fetch origin master:refs/remotes/origin/master
+
+# CFLAGS=-O0 means build with no optimisation.
+# Makes build much quicker for lxml and other dependencies.
+time CFLAGS=-O0 pip install --use-wheel diff_cover
diff --git a/Scripts/diffcover.sh b/Scripts/diffcover-report.sh
similarity index 66%
rename from Scripts/diffcover.sh
rename to Scripts/diffcover-report.sh
index a573c97d4..dacc8b42f 100755
--- a/Scripts/diffcover.sh
+++ b/Scripts/diffcover-report.sh
@@ -1,4 +1,3 @@
-time CFLAGS=-O0 pip install --use-wheel diff_cover
 coverage xml
 diff-cover coverage.xml
 diff-quality --violation=pep8