diff --git a/requirements.txt b/requirements.txt
index 05c8d9c..e04b20f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,7 @@
-cairocffi
-pyserial
-pyhull
-Shapely
+cairocffi==1.2.0
+cffi==1.14.4
+numpy==1.19.5
+pycparser==2.20
+pyhull==2015.2.1
+pyserial==3.5
+Shapely==1.7.1
\ No newline at end of file