@@ -83,8 +83,12 @@ matrix:
         - EXTRAREQS='-r requirements/testing/travis36.txt'
     - python: 3.7
       sudo: true
+      env:
+        - DELETE_FONT_CACHE=1
     - python: "nightly"
-      env: PRE=--pre
+      env:
+        - PRE=--pre
+        - DELETE_FONT_CACHE=1
     - os: osx
       language: generic  # https://github.com/travis-ci/travis-ci/issues/2312
       only: master