diff --git a/prody/tests/proteins/test_insty.py b/prody/tests/proteins/test_insty.py
index 7c9e81cd5..029ff6a85 100644
--- a/prody/tests/proteins/test_insty.py
+++ b/prody/tests/proteins/test_insty.py
@@ -53,7 +53,8 @@ def testAllInteractionsSave(self):
         """Test for saving and loading all types of interactions."""
         if prody.PY3K:
             self.INTERACTIONS_ALL = InteractionsTrajectory()
-            self.data_all = self.INTERACTIONS_ALL.calcProteinInteractionsTrajectory(self.ATOMS)
+            self.data_all = np.array(self.INTERACTIONS_ALL.calcProteinInteractionsTrajectory(self.ATOMS,
+                                                                                             stop_frame=13))
 
             np.save('test_2k39_all.npy', np.array(self.data_all, dtype=object), allow_pickle=True)