diff --git a/Tools/environment_install/install-prereqs-arch.sh b/Tools/environment_install/install-prereqs-arch.sh
index 908fc08c37..1b901c2158 100755
--- a/Tools/environment_install/install-prereqs-arch.sh
+++ b/Tools/environment_install/install-prereqs-arch.sh
@@ -26,7 +26,7 @@ BASE_PKGS="base-devel ccache git gsfonts tk wget gcc"
 SITL_PKGS="python-pip python-setuptools python-wheel wxpython opencv python-numpy python-scipy"
 PX4_PKGS="lib32-glibc zip zlib ncurses"
 
-PYTHON_PKGS="future lxml pymavlink MAVProxy argparse matplotlib pyparsing geocoder pyserial empy"
+PYTHON_PKGS="future lxml pymavlink MAVProxy pexpect argparse matplotlib pyparsing geocoder pyserial empy"
 
 # GNU Tools for ARM Embedded Processors
 # (see https://launchpad.net/gcc-arm-embedded/)