diff --git a/assets/sw-register.js b/assets/sw-register.js
index 0b71f03..b67dbfd 100644
--- a/assets/sw-register.js
+++ b/assets/sw-register.js
@@ -1,4 +1,4 @@
-{{ $swJS := resources.Get "sw.js" | resources.ExecuteAsTemplate "sw.js" . }}
+{{- $swJS := resources.Get "sw.js" | resources.ExecuteAsTemplate "sw.js" . -}}
 if (navigator.serviceWorker) {
   navigator.serviceWorker.register(
     "{{ $swJS.RelPermalink }}", 
diff --git a/assets/sw.js b/assets/sw.js
index 0e7b0cf..2ff11fc 100644
--- a/assets/sw.js
+++ b/assets/sw.js
@@ -1,8 +1,10 @@
 const cacheName = self.location.pathname
 const pages = [
+{{ if eq .Site.Params.BookServiceWorker "precache" }}
   {{ range .Site.AllPages -}}
   "{{ .RelPermalink }}",
-  {{ end }}
+  {{ end -}}
+{{ end }}
 ];
 
 self.addEventListener("install", function (event) {