diff --git a/platform/firefox/manifest.json b/platform/firefox/manifest.json
index e29cd9d..2f47a97 100644
--- a/platform/firefox/manifest.json
+++ b/platform/firefox/manifest.json
@@ -61,7 +61,8 @@
         "default_icon": {
             "16": "img/icon_16.png",
             "128": "img/icon_128.png"
-        }
+        },
+        "open_at_install": false
     },
     "version": "0.9.9"
 }
diff --git a/tools/make-firefox-meta.py b/tools/make-firefox-meta.py
index eb25fc9..8c03556 100755
--- a/tools/make-firefox-meta.py
+++ b/tools/make-firefox-meta.py
@@ -30,6 +30,11 @@ if match:
     webext_manifest['version'] = match.group(1) + builttype
 else:
     webext_manifest['version'] = version
+    # https://bugzilla.mozilla.org/show_bug.cgi?id=1459007
+    # By design Firefox opens the sidebar with new installation of
+    # uMatrix when sidebar_action is present in the manifest.
+    # Remove sidebarAction support for stable release of uBO.
+    del webext_manifest['sidebar_action']
 
 with open(webext_manifest_file, 'w') as f2:
     json.dump(webext_manifest, f2, indent=2, separators=(',', ': '), sort_keys=True)