diff --git a/tools/travis_install_optional.sh b/tools/travis_install_optional.sh
index 989b9d95..4b544a33 100755
--- a/tools/travis_install_optional.sh
+++ b/tools/travis_install_optional.sh
@@ -34,7 +34,7 @@ if [[ $TRAVIS_PYTHON_VERSION != 3.2 ]]; then
 fi
 
 # Install SimpleITK from wheelhouse if available (not 3.2 or 3.4)
-if [[ ($TRAVIS_PYTHON_VERSION =~ 3\.[24] ]]; then
+if [[ $TRAVIS_PYTHON_VERSION =~ 3\.[24] ]]; then
     echo "SimpleITK unavailable on $TRAVIS_PYTHON_VERSION"
 else
     pip install -q SimpleITK $WHEELHOUSE