diff --git a/.travis.yml b/.travis.yml
index 878a6e3b88..17c526cc4e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,6 +13,7 @@ sudo: false
 
 env:
   - TEST_TARGET=default
+  - TEST_TARGET=default COVERAGE=true
   - TEST_TARGET=default TEST_MINIMAL=true
   - TEST_TARGET=coding
   - TEST_TARGET=example
@@ -106,10 +107,14 @@ install:
 
 script:
   - if [[ $TEST_TARGET == 'default' ]]; then
-      SITECUSTOMIZE=$PREFIX/lib/python$TRAVIS_PYTHON_VERSION/site-packages/sitecustomize.py;
-      echo 'import coverage; coverage.process_startup()' > "$SITECUSTOMIZE";
-      export COVERAGE_PROCESS_START="$PWD/.coveragerc";
-      coverage run --concurrency=multiprocessing -pm iris.tests.runner --default-tests --system-tests --print-failed-images;
+      if [[ $COVERAGE == true ]]; then
+        SITECUSTOMIZE=$PREFIX/lib/python$TRAVIS_PYTHON_VERSION/site-packages/sitecustomize.py;
+        echo 'import coverage; coverage.process_startup()' > "$SITECUSTOMIZE";
+        export COVERAGE_PROCESS_START="$PWD/.coveragerc";
+        coverage run --concurrency=multiprocessing -pm iris.tests.runner --default-tests --system-tests --print-failed-images;
+      else
+        python -m iris.tests.runner --default-tests --system-tests --print-failed-images;
+      fi
     fi
   - if [[ $TEST_TARGET == 'example' ]]; then
       python -m iris.tests.runner --example-tests --print-failed-images;
@@ -133,5 +138,4 @@ script:
       python setup.py test --coding-tests;
     fi
 after_success:
-  - coverage combine
-  - coveralls
+  - [[ $COVERAGE == true ]] && { coverage combine; coveralls; }
diff --git a/conda-requirements.txt b/conda-requirements.txt
index 3718be0081..c0590055b5 100644
--- a/conda-requirements.txt
+++ b/conda-requirements.txt
@@ -5,7 +5,7 @@ netcdf4
 numpy
 pyke
 udunits2
-cf_units
+cf_units=1.1.0
 
 setuptools