diff --git a/Gemfile b/Gemfile
index 98f5a7e7b..2672e0aaf 100644
--- a/Gemfile
+++ b/Gemfile
@@ -46,7 +46,7 @@ gem 'gibbon', '~>1.2.0'            # for Mailchimp newsletter subscriptions
 
 # Maps
 gem 'leaflet-rails'
-gem 'rails-assets-leaflet.markercluster'
+gem 'rails-assets-leaflet.markercluster', source: 'https://rails-assets.org'
 
 gem 'pg', '< 1.0.0'                # Upstream bug, see https://github.com/Growstuff/growstuff/pull/1539
 gem 'ruby-units'                   # for unit conversion
diff --git a/Gemfile.lock b/Gemfile.lock
index b6eb02eaf..5dc18108e 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,5 +1,6 @@
 GEM
   remote: https://rubygems.org/
+  remote: https://rails-assets.org/
   specs:
     abstract_type (0.0.7)
     actioncable (5.2.2.1)
@@ -631,7 +632,7 @@ DEPENDENCIES
   puma
   rack-protection (>= 2.0.1)
   rails (= 5.2.2.1)
-  rails-assets-leaflet.markercluster
+  rails-assets-leaflet.markercluster!
   rails-controller-testing
   rails_12factor
   rake (>= 10.0.0)