diff --git a/requirements.txt b/requirements.txt
index 9d614d7a06..09107182e5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -96,6 +96,9 @@ mypy==0.931 \
     --hash=sha256:e839191b8da5b4e5d805f940537efcaa13ea5dd98418f06dc585d2891d228cf0 \
     --hash=sha256:f9fe20d0872b26c4bba1c1be02c5340de1019530302cf2dcc85c7f9fc3252ae0 \
     --hash=sha256:ff3bf387c14c805ab1388185dd22d6b210824e164d4bb324b195ff34e322d166
+pyserial==3.4 \
+    --hash=sha256:6e2d401fdee0eab996cf734e67773a0143b932772ca8b42451440cfed942c627 \
+    --hash=sha256:e0770fadba80c31013896c7e6ef703f72e7834965954a78e71a3049488d4d7d8
 
 ### Indirect requirements ###
 ifaddr==0.1.7 \