diff --git a/pubspec.yaml b/pubspec.yaml
index d208a277a4e..ea88fad6659 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -115,9 +115,7 @@ melos:
       description: Re-generate all golden test files
 
     devtools-build:
-      run: melos exec -- dart run devtools_extensions build_and_copy --source=. --dest=../flame/extension/devtools
-      packageFilters:
-        scope: flame_devtools
+      run: ./scripts/devtools-build.sh
       description: Builds the devtools and copies the build directory to the Flame package.
 
     devtools-simulator:
diff --git a/scripts/devtools-build.sh b/scripts/devtools-build.sh
new file mode 100755
index 00000000000..0577247727a
--- /dev/null
+++ b/scripts/devtools-build.sh
@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+set -e
+
+# Builds the Flame DevTools extension and copies the output into the flame
+# package, mirroring `dart run devtools_extensions build_and_copy` but without
+# the deprecated `--pwa-strategy` flag that the upstream command still passes.
+
+root_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+source_dir="$root_dir/packages/flame_devtools"
+destination_dir="$root_dir/packages/flame/extension/devtools/build"
+
+echo "[devtools-build] Building the extension Flutter web app..."
+(
+  cd "$source_dir"
+  flutter build web --release --no-tree-shake-icons
+)
+
+if [[ -d "$source_dir/build/web/canvaskit" ]]; then
+  echo "[devtools-build] Setting canvaskit permissions..."
+  chmod 0755 "$source_dir/build/web/canvaskit/canvaskit.js" \
+    "$source_dir/build/web/canvaskit/canvaskit.wasm"
+fi
+
+echo "[devtools-build] Replacing the existing extension build with the new one..."
+rm -rf "$destination_dir"
+mkdir -p "$destination_dir"
+cp -R "$source_dir/build/web/." "$destination_dir"
+
+echo "[devtools-build] Successfully copied extension assets to \"$destination_dir\""