diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2a59845..eade4dd 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -32,7 +32,7 @@ jobs:
     - name: Install test dependencies
       run: |
         python -m pip install --upgrade pip
-        pip install setuptools wheel twisted pymodbus
+        pip install setuptools wheel twisted pyserial pymodbus
         sudo apt-get install -y socat
 
     - name: Run tests