diff --git a/docker/kasm/Dockerfile b/docker/kasm/Dockerfile
index ad92134bafcfd38d7ce0573ad712d74a74602b5c..9659311b5f96d7673ed092364ea022ed2072453a 100644
--- a/docker/kasm/Dockerfile
+++ b/docker/kasm/Dockerfile
@@ -14,7 +14,7 @@ ARG ANACONDA_VERS=Anaconda3-2024.02-1
 ARG KASM_USER
 
 
-COPY <<EOF /etc/apt/preferences.d/firefox-deb-nosnap
+RUN cat <<EOF > /etc/apt/preferences.d/firefox-deb-nosnap
 Package: firefox*
 Pin: release o=Ubuntu*
 Pin-Priority: -1