diff --git a/.travis.yml b/.travis.yml
index a462064..e1032a6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -32,4 +32,4 @@ install:
   - "sudo apt-get install zsh"
 
 # Run the tests.
-script: "make tests"
+script: "make tests PYENV="
diff --git a/Makefile b/Makefile
index 13ac11a..342d213 100644
--- a/Makefile
+++ b/Makefile
@@ -1,9 +1,10 @@
 .PHONY: itests tests
 
+PYENV ?= . .pyenv/bin/activate &&
 TESTS ?= tests
 
 itests:
 	${MAKE} tests CRAM_OPTS=-i
 
 tests:
-	. .pyenv/bin/activate && ZDOTDIR="${PWD}/tests" cram ${CRAM_OPTS} --shell=zsh ${TESTS}
+	${PYENV} ZDOTDIR="${PWD}/tests" cram ${CRAM_OPTS} --shell=zsh ${TESTS}