diff --git a/msmbuilder/tests/data_init b/msmbuilder/tests/data_init.py
similarity index 87%
rename from msmbuilder/tests/data_init
rename to msmbuilder/tests/data_init.py
index 76d2b8a7..8263d47a 100644
--- a/msmbuilder/tests/data_init
+++ b/msmbuilder/tests/data_init.py
@@ -5,4 +5,4 @@
 FsPeptide().get().trajectories
 MetEnkephalin().get().trajectories
 DoubleWell(random_state=0).get().trajectories
-MullerPotential(random_state=0).get().trajectories
\ No newline at end of file
+MullerPotential(random_state=0).get().trajectories