diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 8acd9167..e838b9b5 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -108,7 +108,7 @@ JS build. If you change anything under `strix/viewer_src/`, rebuild and commit
 the output:
 
 ```bash
-make viewer   # or: npm --prefix strix/viewer_src ci && npm --prefix strix/viewer_src run build
+make viewer   # or: cd strix/viewer_src && npm ci && npm run build
 ```
 
 Commit both the source change and the regenerated `strix/viewer/viewer_dist/`.
diff --git a/Makefile b/Makefile
index b9b77cb0..708aacc8 100644
--- a/Makefile
+++ b/Makefile
@@ -69,8 +69,7 @@ clean:
 
 viewer:
 	@echo "🖥️  Building the local-viewer SPA..."
-	npm --prefix strix/viewer_src ci
-	npm --prefix strix/viewer_src run build
+	cd strix/viewer_src && npm ci && npm run build
 	@echo "✅ Viewer built to strix/viewer/viewer_dist/ (commit the changes)."
 
 dev: format lint type-check
diff --git a/strix/viewer/cli.py b/strix/viewer/cli.py
index 94eb07a4..eb37951a 100644
--- a/strix/viewer/cli.py
+++ b/strix/viewer/cli.py
@@ -58,8 +58,7 @@ def run_view(argv: list[str]) -> None:
     if not bundle_is_built():
         console.print(
             "[bold red]Viewer UI is not built.[/]\n"
-            "Build it with: [cyan]npm --prefix strix/viewer_src ci && "
-            "npm --prefix strix/viewer_src run build[/]"
+            "Build it with: [cyan]cd strix/viewer_src && npm ci && npm run build[/]"
         )
         raise SystemExit(1)