diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index e88712f..de5c465 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -21,7 +21,8 @@ before_script:
         nasm \
         pkg-config \
         texinfo \
-        wget &&
+        wget \
+        zstd &&
     curl https://sh.rustup.rs -sSf | sh -s -- -y --default-toolchain none
 
 img:
diff --git a/mk/ci.mk b/mk/ci.mk
index 976343a..1dbb3ef 100644
--- a/mk/ci.mk
+++ b/mk/ci.mk
@@ -8,6 +8,7 @@ ci-img: FORCE
 	rm -rf $(IMG_DIR)
 	mkdir -p $(IMG_DIR)
 	$(MAKE) demo desktop server
+	cd $(IMG_DIR) && zstd --rm *
 	cd $(IMG_DIR) && sha256sum -b * > SHA256SUM
 
 # The name of the target must match the name of the filesystem config file