diff --git a/.travis-ci.sh b/.travis-ci.sh
index b1039401..d12db8c6 100755
--- a/.travis-ci.sh
+++ b/.travis-ci.sh
@@ -18,6 +18,9 @@ else
     then
         brew update
 
+        # see https://github.com/Homebrew/homebrew-core/issues/26358
+        brew upgrade python
+
         # build dependencies (Mac OS X)
         brew install ocaml opam
 
diff --git a/.travis.yml b/.travis.yml
index aa7fc44c..dc9acd8d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -21,6 +21,9 @@ matrix:
     # testing only basic install on osx with latest homebrew formulas
     - os: osx
       env: OCAML_VERSION=homebrew
+      before_script:
+        - gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB
+        - rvm get head  # workaround for https://github.com/travis-ci/travis-ci/issues/6307
 branches:
   only:
     - master