diff --git a/requirements.txt b/requirements.txt
index fad83ad6..a6087b3f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,7 +6,7 @@ h5py>=2.5
 click>=7
 cytoolz
 multiprocess
-biopython
+biopython<1.77
 pyfaidx
 pypairix
 asciitree