diff --git a/extensions/chromium/runet-censorship-bypass/src/extension-common/15-firefox-proxy-settings.js b/extensions/chromium/runet-censorship-bypass/src/extension-common/15-firefox-proxy-settings.js
new file mode 100644
index 0000000..df44df1
--- /dev/null
+++ b/extensions/chromium/runet-censorship-bypass/src/extension-common/15-firefox-proxy-settings.js
@@ -0,0 +1,85 @@
+'use strict';
+
+if (window.apis.platform.ifFirefox) {
+
+  const prefix = 'firefox-only';
+
+  const ffxStorage = {
+    get(keys) {
+      return new Promise((resolve) => (
+        chrome.storage.local.get(
+          keys,
+          window.utils.getOrDie(resolve),
+        )
+      ));
+    },
+    set(items) {
+      return new Promise((resolve) => (
+        chrome.storage.local.set(items, resolve)
+      ));
+    },
+    remove(keys) {
+      return new Promise((resolve) => (
+        chrome.storage.local.remove(keys, resolve)
+      ));
+    },
+  };
+
+  const originalSet = chrome.proxy.settings.set.bind( chrome.proxy.settings );
+  chrome.proxy.settings.set = function(details, cb) {
+    const pac = window.utils.getProp(details, 'value.pacScript') || {};
+    if (!(pac && pac.data)) {
+      return originalSet(details, cb);
+    }
+
+    const blob = new Blob([pac.data], { type : 'application/x-ns-proxy-autoconfig' });
+    const blobUrl = URL.createObjectURL(blob);
+    originalSet({
+      value: {
+        proxyType: 'autoConfig',
+        autoConfigUrl: blobUrl,
+      },
+    }, window.utils.chromified( async (err) => {
+      if (err) {
+        throw err;
+      }
+      await ffxStorage.set({ [`${prefix}-pacData`]: pac.data });
+      cb();
+    }));
+  };
+
+  const originalGet = chrome.proxy.settings.get.bind( chrome.proxy.settings );
+  chrome.proxy.settings.get = function(details, cb) {
+    originalGet(details, window.utils.chromified((err, originalDetails) => {
+      if (err) {
+        throw err;
+      }
+      const autoConfigUrl = window.utils.getProp(originalDetails, 'value.autoConfigUrl');
+      if (!autoConfigUrl) {
+        return cb(originalDetails);
+      }
+      window.apis.httpLib.get(autoConfigUrl, async (err, pacData) => {
+        if (err) {
+          pacData = await ffxStorage.get(`${prefix}-pacData`);
+        }
+        cb(Object.assign(
+          originalDetails,
+          {
+            value: {
+              mode: 'pac_script',
+              pacScript: {
+                data: pacData,
+              },
+            },
+          }
+        ));
+      });
+    }));
+  };
+
+  const originalClear = chrome.proxy.settings.clear.bind( chrome.proxy.settings );
+  chrome.proxy.settings.clear = async function(details, cb) {
+    await ffxStorage.remove(`${prefix}-pacData`);
+    originalClear(details, cb);
+  };
+}
diff --git a/extensions/chromium/runet-censorship-bypass/src/extension-common/35-pac-kitchen-api.js b/extensions/chromium/runet-censorship-bypass/src/extension-common/35-pac-kitchen-api.js
index 71ec0df..9c1bae5 100644
--- a/extensions/chromium/runet-censorship-bypass/src/extension-common/35-pac-kitchen-api.js
+++ b/extensions/chromium/runet-censorship-bypass/src/extension-common/35-pac-kitchen-api.js
@@ -544,7 +544,10 @@ ${
         if (
           details && details.levelOfControl === 'controlled_by_this_extension'
         ) {
-          return chrome.proxy.settings.set(details, chromified(cb));
+          const pac = window.utils.getProp(details, 'value.pacScript');
+          if (pac && pac.data) {
+            return chrome.proxy.settings.set(details, chromified(cb));
+          }
         }
 
         kitchenState(ifIncontinence, true);
@@ -621,50 +624,21 @@ ${
   const originalSet = chrome.proxy.settings.set.bind( chrome.proxy.settings );
 
   chrome.proxy.settings.set = function(details, cb) {
-
-    const pac = window.utils.getProp(details, 'value.pacScript') || {};
-    const autoConfigUrl = window.utils.getProp(details, 'value.autoConfigUrl');
-    const ifNothingToCook = !(pac && pac.data || autoConfigUrl);
-    if (ifNothingToCook) {
+    const pac = window.utils.getProp(details, 'value.pacScript');
+    if (!(pac && pac.data)) {
       return originalSet(details, cb);
     }
-    const getPacData = (getPacCb) =>
-      pac.data ? getPacCb(null, pac.data) : window.apis.httpLib.get(autoConfigUrl, getPacCb);
+    const pacMods = getCurrentConfigs();
+    pac.data = pacKitchen.cook( pac.data, pacMods );
+    originalSet({value: details.value}, window.utils.chromified((err) => {
 
-    getPacData((err, pacData) => {
       if (err) {
-        cb(err);
-        return;
+        throw err;
       }
-      const pacMods = getCurrentConfigs();
-      const cookedData = pacKitchen.cook( pacData, pacMods );
-      const setCb = (/* No args. */) => {
+      kitchenState(ifIncontinence, null);
+      cb && cb();
 
-        kitchenState(ifIncontinence, null);
-        cb && cb();
-
-      };
-
-      if (window.apis.platform.ifFirefox) {
-        const autoConfigUrl = `data:application/x-ns-proxy-autoconfig,${escape(cookedData)}`;
-        return originalSet({
-          value: {
-            proxyType: 'autoConfig',
-            autoConfigUrl,
-          },
-        }, setCb);
-      }
-
-      details.value.pacScript.data = cookedData;
-      return originalSet({ value: details.value }, setCb);
-    });
+    }));
   };
 
-  pacKitchen.checkIncontinence();
-  chrome.proxy.settings.onChange.addListener(
-    timeouted(
-      pacKitchen.checkIncontinence.bind(pacKitchen)
-    )
-  );
-
 } // Private namespace ends.
diff --git a/extensions/chromium/runet-censorship-bypass/src/extension-common/manifest.tmpl.json b/extensions/chromium/runet-censorship-bypass/src/extension-common/manifest.tmpl.json
index 0f75361..fe76a68 100644
--- a/extensions/chromium/runet-censorship-bypass/src/extension-common/manifest.tmpl.json
+++ b/extensions/chromium/runet-censorship-bypass/src/extension-common/manifest.tmpl.json
@@ -14,6 +14,7 @@
       "proxy"
     , "alarms"
     , "storage"
+    , "unlimitedStorage"
     , "<all_urls>"
     , "tabs"
     , "contextMenus"
@@ -30,6 +31,7 @@
       , "11-error-handlers-api.js"
       , "12-errors-lib.js"
       , "13-http-lib.js"
+      , "15-firefox-proxy-settings.js"
       ${scripts_2x}
       , "35-pac-kitchen-api.js"
       , "37-sync-pac-script-with-pac-provider-api.js"