diff --git a/app/liquid_tags/runkit_tag.rb b/app/liquid_tags/runkit_tag.rb
index 944282c67..6f80b888c 100644
--- a/app/liquid_tags/runkit_tag.rb
+++ b/app/liquid_tags/runkit_tag.rb
@@ -1,7 +1,7 @@
 class RunkitTag < Liquid::Block
   def initialize(tag_name, markup, tokens)
     super
-    @markup = markup
+    @preamble = ActionView::Base.full_sanitizer.sanitize(markup, tags: [])
   end
 
   def render(context)
@@ -9,7 +9,8 @@ class RunkitTag < Liquid::Block
     parsed_content = content.xpath("//html/body").text
     html = <<~HTML
       <div class="runkit-element">
-        #{parsed_content}
+        <code style="display: none">#{@preamble}</code>
+        <code>#{parsed_content}</code>
       </div>
     HTML
     html
@@ -18,15 +19,15 @@ class RunkitTag < Liquid::Block
   def self.special_script
     <<~JAVASCRIPT
       var targets = document.getElementsByClassName("runkit-element");
-      if (targets.length > 0) {
-        for (var i = 0; i < targets.length; i++) {
-          var content = targets[i].textContent;
-          targets[i].innerHTML = "";
-          var notebook = RunKit.createNotebook({
-            element: targets[i],
-            source: content,
-          });
-        }
+      for (var i = 0; i < targets.length; i++) {
+        var preamble = targets[i].children[0].textContent;
+        var content = targets[i].children[1].textContent;
+        targets[i].innerHTML = "";
+        var notebook = RunKit.createNotebook({
+          element: targets[i],
+          source: content,
+          preamble: preamble
+        });
       }
     JAVASCRIPT
   end
@@ -36,16 +37,17 @@ class RunkitTag < Liquid::Block
       var checkRunkit = setInterval(function() {
         if(typeof(RunKit) !== 'undefined') {
           var targets = document.getElementsByClassName("runkit-element");
-          if (targets.length > 0) {
-            for (var i = 0; i < targets.length; i++) {
-              var content = targets[i].textContent;
-              if(/^(\<iframe src)/.test(content) === false) {
-                targets[i].innerHTML = "";
-                var notebook = RunKit.createNotebook({
-                  element: targets[i],
-                  source: content,
-                });
-              }
+          for (var i = 0; i < targets.length; i++) {
+            var wrapperContent = targets[i].textContent;
+            if(/^(\<iframe src)/.test(wrapperContent) === false) {
+              var preamble = targets[i].children[0].textContent;
+              var content = targets[i].children[1].textContent;
+              targets[i].innerHTML = "";
+              var notebook = RunKit.createNotebook({
+                element: targets[i],
+                source: content,
+                preamble: preamble
+              });
             }
           }
           clearInterval(checkRunkit);
diff --git a/app/views/pages/_editor_guide_text.html.erb b/app/views/pages/_editor_guide_text.html.erb
index 33043539a..adf1042e0 100644
--- a/app/views/pages/_editor_guide_text.html.erb
+++ b/app/views/pages/_editor_guide_text.html.erb
@@ -136,7 +136,7 @@
 
     <h3><strong>RunKit Embed</strong></h3>
     <p>Put executable code within a runkit liquid block, as follows:</p>
-    <pre>{% runkit %}<br>console.log("Place javascript here!"); <br>{% endrunkit %} <br></pre>
+    <pre>{% runkit<br>// hidden setup JavaScript code goes in this preamble area<br>const hiddenVar = 42<br>%}<br>// visible, reader-editable JavaScript code goes here<br>console.log(hiddenVar)<br>{% endrunkit %} <br></pre>
 
     <h3><strong>repl.it Embed</strong></h3>
     <p>All you need is the URL after the domain name:</p>
diff --git a/spec/liquid_tags/runkit_tag_spec.rb b/spec/liquid_tags/runkit_tag_spec.rb
index dedf58634..ebf7250c7 100644
--- a/spec/liquid_tags/runkit_tag_spec.rb
+++ b/spec/liquid_tags/runkit_tag_spec.rb
@@ -2,6 +2,12 @@ require "rails_helper"
 
 RSpec.describe RunkitTag, type: :liquid_template do
   describe "#render" do
+    let(:preamble) do
+      <<~CODE
+        const myVar = 9001
+      CODE
+    end
+
     let(:content) do
       <<~CODE
         // GeoJSON!
@@ -11,22 +17,23 @@ RSpec.describe RunkitTag, type: :liquid_template do
       CODE
     end
 
-    def generate_new_liquid(block)
+    def generate_new_liquid(preamble_str, block)
       Liquid::Template.register_tag("runkit", described_class)
-      Liquid::Template.parse("{% runkit %}#{block}{% endrunkit %}")
+      Liquid::Template.parse("{% runkit #{preamble_str}%}#{block}{% endrunkit %}")
     end
 
-    def generate_script(block)
+    def generate_script(preamble_str, block)
       <<~HTML
         <div class="runkit-element">
-          #{block}
+          <code style="display: none">#{preamble_str}</code>
+          <code>#{block}</code>
         </div>
       HTML
     end
 
     it "generates proper div with content" do
-      liquid = generate_new_liquid(content)
-      expect(liquid.render).to eq(generate_script(content))
+      liquid = generate_new_liquid(preamble, content)
+      expect(liquid.render).to eq(generate_script(preamble, content))
     end
   end
 end