diff --git a/requirements.txt b/requirements.txt
index 90f9426..2192e97 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,7 +5,7 @@ six
 h5py
 lmfit
 pandas
-mdtraj<=1.9.1
+mdtraj<=1.8.0
 MDAnalysis
 tqdm
 sphinx