diff --git a/src/output/srcdoc.html b/src/output/srcdoc.html
index 189c19ca..d8723d4a 100644
--- a/src/output/srcdoc.html
+++ b/src/output/srcdoc.html
@@ -6,14 +6,16 @@
         color-scheme: dark;
       }
       body {
-        font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
-          Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
+        font-family:
+          -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu,
+          Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
       }
     </style>
     <!-- PREVIEW-OPTIONS-HEAD-HTML -->
     <script>
       ;(() => {
         let scriptEls = []
+        let lastEvalPromise = null
 
         window.process = { env: {} }
         window.__modules__ = {}
@@ -40,7 +42,15 @@
             send_reply({ action: 'cmd_error', message, stack })
 
           if (action === 'eval') {
+            let evalDone
             try {
+              if (lastEvalPromise) {
+                await lastEvalPromise
+              }
+              lastEvalPromise = new Promise((resolve) => {
+                evalDone = resolve
+              })
+
               if (scriptEls.length) {
                 scriptEls.forEach((el) => {
                   document.head.removeChild(el)
@@ -68,6 +78,9 @@
               send_ok()
             } catch (e) {
               send_error(e.message, e.stack)
+            } finally {
+              lastEvalPromise = null
+              evalDone()
             }
           }