diff --git a/scripts/install_build_env.sh b/scripts/install_build_env.sh
index 0eb2a85..b955d29 100755
--- a/scripts/install_build_env.sh
+++ b/scripts/install_build_env.sh
@@ -4,6 +4,7 @@ python3 -m pip install empy
 python3 -m pip install pymavlink
 python3 -m pip install dronecan
 python3 -m pip install pyserial
+python3 -m pip install pexpect
 wget https://downloads.arduino.cc/arduino-cli/arduino-cli_0.27.1_Linux_64bit.tar.gz
 mkdir -p bin
 (cd bin && tar xvzf ../arduino-cli_0.27.1_Linux_64bit.tar.gz)