diff --git a/Dockerfile.bullseye b/Dockerfile.bullseye
index 5668ee19730486361cf5b386945f8bc46d203bca..9d5088f205f576250b6d10c7f9d67beed951b51b 100644
--- a/Dockerfile.bullseye
+++ b/Dockerfile.bullseye
@@ -6,7 +6,7 @@ RUN apt-get -qq update && \
         lsb-release openjdk-11-jre-headless curl ca-certificates \
         sqlite3 locales-all git \
         python3 python3-venv python3-coverage python3-ldap3 python3-flask python3-flask-sqlalchemy python3-flask-migrate \
-        python3-pip python3-qrcode python3-fido2 python3-oauthlib python3-flask-babel python3-argon2 python3-pytest python3-all python3-pip \
+        python3-pip python3-qrcode python3-fido2 python3-oauthlib python3-flask-babel python3-argon2 python3-pytest python3-pytest-xdist python3-all python3-pip \
         git-buildpackage debhelper dh-python mariadb-server python3-mysqldb python3-requests-oauthlib python3-git libffi-dev && \
     pip3 install pylint html5validator twine build --upgrade && \
     apt-get -qq clean
diff --git a/Dockerfile.buster b/Dockerfile.buster
index ec1cbd2d7ee34f618a9237369ba006005eea2a42..124623216d5c6922fb8f8733ef0f88888c5f84a3 100644
--- a/Dockerfile.buster
+++ b/Dockerfile.buster
@@ -6,7 +6,7 @@ RUN apt-get -qq update && \
         lsb-release openjdk-11-jre-headless curl ca-certificates \
         sqlite3 locales-all git \
         python3 python3-venv python3-coverage python3-ldap3 python3-flask python3-flask-sqlalchemy python3-flask-migrate \
-        python3-pip python3-qrcode python3-fido2 python3-oauthlib python3-flask-babel python3-argon2 python3-pytest python3-all python3-pip \
+        python3-pip python3-qrcode python3-fido2 python3-oauthlib python3-flask-babel python3-argon2 python3-pytest python3-pytest-xdist python3-all python3-pip \
         git-buildpackage debhelper dh-python mariadb-server python3-mysqldb python3-flask-oauthlib python3-requests-oauthlib python3-git libffi-dev && \
     pip3 install pylint html5validator twine build --upgrade && \
     apt-get -qq clean