diff --git a/bundles/build-server/files/crystal b/bundles/build-server/files/crystal
index de49fb0..f542265 100644
--- a/bundles/build-server/files/crystal
+++ b/bundles/build-server/files/crystal
@@ -10,6 +10,7 @@ REPO_NAME=$(jq -r .repository.name <<< $JSON)
 CLONE_URL=$(jq -r .repository.clone_url <<< $JSON)
 BUILD_FILE=$(jq -r .file <<< $ARGS)
 DATE=$(date --utc +%s)
+SSH_OPTIONS='-o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null'
 
 cd ~
 rm -rf "$REPO_NAME"
@@ -20,13 +21,12 @@ shards install
 for ARCH in $(jq -r '.architectures | keys[]' <<< $CONFIG)
 do
   TARGET=$(jq -r .architectures.$ARCH.target <<< $CONFIG)
-  IP=$(jq -r .architectures.$ARCH.ip <<< $CONFIG)
-  BUILD_CMD=$(crystal build "$BUILD_FILE" --cross-compile --target="$TARGET" --release -o "$REPO_NAME")
+  BINARY="$REPO_NAME-$ARCH-$DATE"
 
-  scp -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "$REPO_NAME.o" "build-agent@$IP:~"
-  ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "build-agent@$IP" $BUILD_CMD
-  scp -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "build-agent@$IP:~/$REPO_NAME" .
-  ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "downloads@$DOWNLOAD_SERVER" mkdir -p "~/$REPO_NAME"
-  scp -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "$REPO_NAME" "downloads@$DOWNLOAD_SERVER:~/$REPO_NAME/$REPO_NAME-$ARCH-$DATE"
-  ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "downloads@$DOWNLOAD_SERVER" ln -sf "$REPO_NAME-$ARCH-$DATE" "~/$REPO_NAME/$REPO_NAME-$ARCH-latest"
+  # static, so the binary does not depend on the libraries of a debian release
+  crystal build "$BUILD_FILE" --static --release --target="$TARGET" -o "$BINARY"
+
+  ssh $SSH_OPTIONS "downloads@$DOWNLOAD_SERVER" mkdir -p "~/$REPO_NAME"
+  scp $SSH_OPTIONS "$BINARY" "downloads@$DOWNLOAD_SERVER:~/$REPO_NAME/$BINARY"
+  ssh $SSH_OPTIONS "downloads@$DOWNLOAD_SERVER" ln -sf "$BINARY" "~/$REPO_NAME/$REPO_NAME-$ARCH-latest"
 done
diff --git a/bundles/build-server/metadata.py b/bundles/build-server/metadata.py
index 49ec4d7..87d1cbc 100644
--- a/bundles/build-server/metadata.py
+++ b/bundles/build-server/metadata.py
@@ -24,18 +24,12 @@ defaults = {
 
 
 @metadata_reactor.provides(
-    'build-server',
+    'build-server/download_server_ip',
 )
-def agent_conf(metadata):
+def download_server(metadata):
     download_server = repo.get_node(metadata.get('build-server/download_server'))
     return {
         'build-server': {
-            'architectures': {
-                architecture: {
-                    'ip': str(ip_interface(repo.get_node(conf['node']).metadata.get('network/internal/ipv4')).ip),
-                }
-                    for architecture, conf in metadata.get('build-server/architectures').items()
-            },
             'download_server_ip': str(ip_interface(download_server.metadata.get('network/internal/ipv4')).ip),
         },
     }
diff --git a/bundles/crystal/metadata.py b/bundles/crystal/metadata.py
index 2f98c45..19e4fb7 100644
--- a/bundles/crystal/metadata.py
+++ b/bundles/crystal/metadata.py
@@ -1,16 +1,19 @@
-debian_version = min([node.os_version, (11,)])[0] # FIXME
-
 defaults = {
     'apt': {
         'packages': {
             'crystal': {},
+            # static linking (crystal build --static)
+            'build-essential': {},
+            'libgc-dev': {},
+            'libpcre2-dev': {},
+            'libevent-dev': {},
         },
         'sources': {
             'crystal': {
                 # https://software.opensuse.org/download.html?project=devel%3Alanguages%3Acrystal&package=crystal
-                # curl -fsSL https://download.opensuse.org/repositories/devel:/languages:/crystal/Debian_Testing/Release.key
+                # curl -fsSL https://download.opensuse.org/repositories/devel:/languages:/crystal/Debian_13/Release.key
                 'urls': {
-                    'http://download.opensuse.org/repositories/devel:/languages:/crystal/Debian_Testing/',
+                    f'http://download.opensuse.org/repositories/devel:/languages:/crystal/Debian_{node.os_version[0]}/',
                 },
                 'suites': {
                     '/',
diff --git a/groups/applications/build-server.py b/groups/applications/build-server.py
index eb332d3..2771f87 100644
--- a/groups/applications/build-server.py
+++ b/groups/applications/build-server.py
@@ -1,6 +1,7 @@
 {
     'bundles': {
         'build-server',
+        'crystal',
         'flask',
     },
 }
diff --git a/nodes/home.server.py b/nodes/home.server.py
index 3232a14..4f3292f 100644
--- a/nodes/home.server.py
+++ b/nodes/home.server.py
@@ -12,8 +12,6 @@
         'build-server',
     ],
     'bundles': [
-        'build-agent',
-        #'crystal',
         'gitea',
 #        'gollum',
         'grub',
@@ -53,11 +51,10 @@
             'hostname': 'build.sublimity.de',
             'architectures': {
                 'amd64': {
-                    'node': 'home.server',
                     'target': 'x86_64-unknown-linux-gnu',
                 },
+                # arm64 needs a cross linker and arm64 static libs (multiarch):
                 # 'arm64': {
-                #     'node': 'home.openhab',
                 #     'target': 'aarch64-unknown-linux-gnu',
                 # },
             },