diff --git a/Tools/scripts/build_ci.sh b/Tools/scripts/build_ci.sh
index c82d184d47b5a..21fb6ee4c60f8 100755
--- a/Tools/scripts/build_ci.sh
+++ b/Tools/scripts/build_ci.sh
@@ -422,7 +422,7 @@ for t in $CI_BUILD_TARGET; do
         echo "Building signed firmwares"
         sudo apt-get update
         sudo apt-get install -y python3-dev
-        python3 -m pip install pymonocypher
+        python3 -m pip install pymonocypher==3.1.3.2
         ./Tools/scripts/signing/generate_keys.py testkey
         $waf configure --board CubeOrange-ODID --signed-fw --private-key testkey_private_key.dat
         $waf copter