diff --git a/webextensions/common/constants.js b/webextensions/common/constants.js
index 11603aa97..0a8d76fc5 100644
--- a/webextensions/common/constants.js
+++ b/webextensions/common/constants.js
@@ -343,7 +343,7 @@ export const kDEFAULT_MIN_INDENT = 3;
 export const kGROUP_TAB_URI = browser.runtime.getURL('resources/group-tab.html');
 export const kGROUP_TAB_DEFAULT_TITLE_MATCHER = new RegExp(`^${browser.i18n.getMessage('groupTab_label', '.+')}$`);
 export const kGROUP_TAB_FROM_PINNED_DEFAULT_TITLE_MATCHER = new RegExp(`^${browser.i18n.getMessage('groupTab_fromPinnedTab_label', '.+')}$`);
-export const kSHORTHAND_CUSTOM_URI = /^ext\+treestyletab:([^:?]+)(?:[:?](.*))?(#.*)?$/;
+export const kSHORTHAND_CUSTOM_URI = /^ext\+treestyletab:([^:?#]+)(?:[:?]([^#]*))?(#.*)?$/;
 export const kSHORTHAND_ABOUT_URI = /^about:treestyletab-([^?]+)/;
 export const kSHORTHAND_URIS = {
   tabbar:  browser.runtime.getURL('sidebar/sidebar.html'),