diff --git a/.gitignore b/.gitignore
index cb638e4..8749f63 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 nginx-tmp
 static-tmp
+lock
diff --git a/deploy-static b/deploy-static
index 7c0c8fc..9f2e632 100755
--- a/deploy-static
+++ b/deploy-static
@@ -2,7 +2,14 @@
 
 set -o errexit -o nounset -o pipefail
 
-./process-static
+touch lock
+exec {fd}< lock
+if ! flock -n $fd; then
+    echo deploy_static already locked >&2
+    exit 1
+fi
+
+./process-static $fd
 
 remote=root@matrix.grapheneos.org
 active=$(ssh $remote readlink /srv/element.grapheneos.org)
diff --git a/process-static b/process-static
index 03a1eb7..a912648 100755
--- a/process-static
+++ b/process-static
@@ -3,6 +3,18 @@
 set -o errexit -o nounset -o pipefail
 shopt -s dotglob extglob globstar
 
+if [[ $# -eq 1 ]]; then
+    fd=$1
+else
+    touch lock
+    exec {fd}< lock
+fi
+
+if ! flock -n $fd; then
+    echo deploy_static already locked >&2
+    exit 1
+fi
+
 export PATH="$PWD/node_modules/.bin:$PATH"
 
 rm -rf nginx-tmp