diff --git a/chrome/content/zotero/lookup.js b/chrome/content/zotero/lookup.js
index 6fc52b44dd..a877b3b169 100644
--- a/chrome/content/zotero/lookup.js
+++ b/chrome/content/zotero/lookup.js
@@ -225,6 +225,12 @@ const Zotero_Lookup = new function () {
 		//switch textboxes
 		mlPanel.setAttribute("collapsed", !on);
 		slPanel.setAttribute("collapsed", !!on);
+
+		// Resize arrow box to fit content
+		var panel = document.getElementById("zotero-lookup-panel");
+		var box = panel.firstChild;
+		panel.sizeTo(box.scrollWidth, box.scrollHeight);
+
 		dest.focus();
 		return dest;
 	}