diff --git a/cmake/platforms/emscripten.cmake b/cmake/platforms/emscripten.cmake
index 70aa5c9..898d3ea 100644
--- a/cmake/platforms/emscripten.cmake
+++ b/cmake/platforms/emscripten.cmake
@@ -122,6 +122,8 @@ function(build_platform_extras)
     install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${name}-manifest.webapp
       RENAME manifest.webapp
       DESTINATION kaios/${name})
+    install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/kaios/kaiads-glue.js
+      DESTINATION kaios/${name})
     if (HALIBUT)
       install(DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/help
         DESTINATION kaios/${name})
diff --git a/kaios/apppage.pl b/kaios/apppage.pl
index 8f72ee6..251ab2f 100755
--- a/kaios/apppage.pl
+++ b/kaios/apppage.pl
@@ -13,7 +13,10 @@ print <<EOF;
 <meta http-equiv="Content-Type" content="text/html; charset=ASCII" />
 <meta name="theme-color" content="rgb(50,50,50)" />    
 <title>${displayname}</title>
+<!-- The KaiAds scripts are only present in Kai Store versions. -->
+<script src="kaiads.v5.min.js"></script>
 <script defer type="text/javascript" src="${name}.js"></script>
+<script defer type="text/javascript" src="kaiads-glue.js"></script>
 <!-- Override some defaults for small screens -->
 <script id="environment" type="application/json">
 { "PATTERN_DEFAULT": "10x10",
diff --git a/kaios/kaiads-glue.js b/kaios/kaiads-glue.js
new file mode 100644
index 0000000..1eb30aa
--- /dev/null
+++ b/kaios/kaiads-glue.js
@@ -0,0 +1,58 @@
+// Glue connecting Puzzles to the KaiAds API.
+//
+// The Kai Store requires that we support advertisements through
+// KaiAds.  To avoid polluting the Puzzles core with this, the
+// relevant code is largely confined to this file.  It can then be
+// included in builds that are destined for the Kai Store and left out
+// of others.  The main puzzle code, and the KaiAds API (as supplied
+// by Kai Technologies) should be loaded before this file.
+
+
+(function() {
+    // To run, we need to be on KaiOS with the KaiAds SDK and the
+    // Open Web Apps API.
+    if (!getKaiAd || !navigator.mozApps ||
+        navigator.userAgent.toLowerCase().indexOf('kaios') == -1) return;
+    // If those prerequisites are satisfied, install the button.
+    var advertbutton = document.createElement("button");
+    advertbutton.type = "button";
+    advertbutton.textContent = "Display an advert...";
+    advertbutton.disabled = true;
+    var advertli = document.createElement("li");
+    advertli.appendChild(advertbutton);
+    menuform.querySelector("ul").appendChild(advertli);
+    // Now work out whether we're installed from the Store (and hence
+    // want real adverts) or not (and hence want test ones).
+    var selfrequest = navigator.mozApps.getSelf();
+    selfrequest.onerror = function() {
+        console.log("Error getting own app record: ", selfrequest.error.name);
+        // Leave the button disabled.
+    };
+    selfrequest.onsuccess = function() {
+        var testmode = selfrequest.result.installOrigin !=
+            "app://kaios-plus.kaiostech.com";
+
+        advertbutton.addEventListener("click", function(e) {
+            // The KaiAds SDK provides this function.
+            getKaiAd({
+                publisher: 'dac9c115-ec42-4175-ac5e-47e118cc541b',
+                test: testmode ? 1 : 0,
+                timeout: 5000,
+                onready: function(ad) {
+                    ad.on('close', function () {
+                        // KaiAds adds inline styles to the body and doesn't
+                        // remove them, so we do it ourselves.
+                        document.body.style = '';
+                        onscreen_canvas.focus();
+                    });
+                    ad.call('display');
+                },
+                onerror: function(err) {
+                    alert(`Sorry; no advert available (KaiAds error ${err}).`);
+                    onscreen_canvas.focus(); // Close the menu.
+                }
+            });
+        });
+        advertbutton.disabled = false;
+    };
+})();
diff --git a/kaios/manifest.pl b/kaios/manifest.pl
index 458c724..510f535 100755
--- a/kaios/manifest.pl
+++ b/kaios/manifest.pl
@@ -56,5 +56,15 @@ print encode_json({
     categories => ["games"],
     type => "web",
     cursor => JSON::PP::false,
+    # These permissions could be removed on builds without KaiAds,
+    # but that's a bit complicated.
+    permissions => {
+        mobiledata => {
+            description => "Required to display advertisements"
+        },
+        wifidata => {
+            description => "Required to display advertisements"
+        },
+    },
     $decvers ? (version => $decvers) : (),
 })