diff --git a/hs b/hs
index 70bd544..8ecc5e0 100755
--- a/hs
+++ b/hs
@@ -6,13 +6,17 @@ set -euo pipefail
 
 IMAGE="${HAWAT_HASKELL_TOOLS_IMAGE:-ghcr.io/flipstone/haskell-tools:debian-ghc-9.10.3-5d6640d}"
 PROJECT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-STACK_ROOT_HOST="${PROJECT_DIR}/.stack-root"
 
-mkdir -p "${STACK_ROOT_HOST}"
+# Named Docker volume shared across all worktrees so cached
+# GHC/dependencies don't need rebuilding per worktree.
+STACK_ROOT_VOLUME="roux-stack-root"
+
+docker volume inspect "${STACK_ROOT_VOLUME}" > /dev/null 2>&1 || \
+  docker volume create "${STACK_ROOT_VOLUME}" > /dev/null
 
 exec docker run --rm -i $([ -t 0 ] && printf -- -t) \
   -v "${PROJECT_DIR}:/work" \
-  -v "${STACK_ROOT_HOST}:/stack-root" \
+  -v "${STACK_ROOT_VOLUME}:/stack-root" \
   -e STACK_ROOT=/stack-root \
   -w /work \
   "${IMAGE}" \