diff --git a/app/renderer/main.html b/app/renderer/main.html
index c848e697..40565def 100644
--- a/app/renderer/main.html
+++ b/app/renderer/main.html
@@ -2,6 +2,10 @@
 <html lang="en" class="responsive desktop">
   <head>
     <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
+    <meta
+      http-equiv="Content-Security-Policy"
+      content="default-src 'none'; connect-src 'self'; font-src 'self'; img-src 'self' data:; script-src 'self'; style-src 'self' 'unsafe-inline'"
+    />
     <meta name="viewport" content="width=device-width" />
     <title>Zulip</title>
     <link rel="stylesheet" href="css/fonts.css" />
diff --git a/app/renderer/network.html b/app/renderer/network.html
index d52c30bb..a840a7d9 100644
--- a/app/renderer/network.html
+++ b/app/renderer/network.html
@@ -2,6 +2,10 @@
 <html lang="en" class="responsive desktop">
   <head>
     <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
+    <meta
+      http-equiv="Content-Security-Policy"
+      content="default-src 'none'; connect-src 'self'; img-src 'self'; script-src 'self'; style-src 'self'"
+    />
     <meta name="viewport" content="width=device-width" />
     <title>Zulip - Network Troubleshooting</title>
     <link
