diff --git a/app/helpers/importmap/importmap_tags_helper.rb b/app/helpers/importmap/importmap_tags_helper.rb
index ce3da83..d4d2b4f 100644
--- a/app/helpers/importmap/importmap_tags_helper.rb
+++ b/app/helpers/importmap/importmap_tags_helper.rb
@@ -1,9 +1,9 @@
 module Importmap::ImportmapTagsHelper
   # Setup all script tags needed to use an importmap-powered entrypoint (which defaults to application.js)
-  def javascript_importmap_tags(entry_point = "application", shim: true)
+  def javascript_importmap_tags(entry_point = "application", shim: true, importmap: Rails.application.importmap)
     safe_join [
-      javascript_inline_importmap_tag,
-      javascript_importmap_module_preload_tags,
+      javascript_inline_importmap_tag(importmap.to_json(resolver: self)),
+      javascript_importmap_module_preload_tags(importmap),
       (javascript_importmap_shim_nonce_configuration_tag if shim),
       (javascript_importmap_shim_tag if shim),
       javascript_import_module_tag(entry_point)
@@ -34,7 +34,7 @@ def javascript_importmap_shim_tag(minimized: true)
   # Import a named JavaScript module(s) using a script-module tag.
   def javascript_import_module_tag(*module_names)
     imports = Array(module_names).collect { |m| %(import "#{m}") }.join("\n")
-    tag.script imports.html_safe, 
+    tag.script imports.html_safe,
       type: "module", nonce: request&.content_security_policy_nonce
   end
 
diff --git a/test/importmap_tags_helper_test.rb b/test/importmap_tags_helper_test.rb
index b28bb81..74f75d8 100644
--- a/test/importmap_tags_helper_test.rb
+++ b/test/importmap_tags_helper_test.rb
@@ -55,4 +55,18 @@ def content_security_policy_nonce
   ensure
     @request = nil
   end
+
+  test "using a custom importmap" do
+    importmap = Importmap::Map.new
+    importmap.pin "foo", preload: true
+    importmap.pin "bar", preload: false
+    importmap_html = javascript_importmap_tags("foo", importmap: importmap)
+
+    assert_includes importmap_html, %{<script type="importmap" data-turbo-track="reload">}
+    assert_includes importmap_html, %{"foo": "/foo.js"}
+    assert_includes importmap_html, %{"bar": "/bar.js"}
+    assert_includes importmap_html, %{<link rel="modulepreload" href="/foo.js">}
+    refute_includes importmap_html, %{<link rel="modulepreload" href="/bar.js">}
+    assert_includes importmap_html, %{<script type="module">import "foo"</script>}
+  end
 end