diff --git a/tools/travis_install_optional.sh b/tools/travis_install_optional.sh
index fa4df268..5160d9fb 100755
--- a/tools/travis_install_optional.sh
+++ b/tools/travis_install_optional.sh
@@ -10,7 +10,7 @@ if [[ $TRAVIS_PYTHON_VERSION == 2.7* ]]; then
     # http://stackoverflow.com/a/9716100
     LIBS=( PyQt4 sip.so )
 
-    VAR=( $(which -a $TRAVIS_PYTHON_VERSION) )
+    VAR=( $(which -a python$TRAVIS_PYTHON_VERSION) )
 
     GET_PYTHON_LIB_CMD="from distutils.sysconfig import get_python_lib; print (get_python_lib())"
     LIB_VIRTUALENV_PATH=$(python -c "$GET_PYTHON_LIB_CMD")