diff --git a/public/manifest.firefox.json b/public/manifest.firefox.json
index ad8d567..d676206 100644
--- a/public/manifest.firefox.json
+++ b/public/manifest.firefox.json
@@ -12,7 +12,7 @@
   "content_scripts": [
     {
       "js": ["content.js"],
-      "matches": ["<all_urls>"],
+      "matches": ["<all_urls>", "file://*/*"],
       "all_frames": true
     }
   ],
diff --git a/public/manifest.json b/public/manifest.json
index 8756847..9a22aba 100644
--- a/public/manifest.json
+++ b/public/manifest.json
@@ -13,7 +13,7 @@
   "content_scripts": [
     {
       "js": ["content.js"],
-      "matches": ["<all_urls>"],
+      "matches": ["<all_urls>", "file://*/*"],
       "all_frames": true
     }
   ],
diff --git a/public/manifest.thunderbird.json b/public/manifest.thunderbird.json
index 9237257..2944fad 100644
--- a/public/manifest.thunderbird.json
+++ b/public/manifest.thunderbird.json
@@ -18,7 +18,7 @@
   "content_scripts": [
     {
       "js": ["content.js"],
-      "matches": ["<all_urls>"],
+      "matches": ["<all_urls>", "file://*/*"],
       "all_frames": true
     }
   ],