diff --git a/chrome/content/zotero/xpcom/dataDirectory.js b/chrome/content/zotero/xpcom/dataDirectory.js
index 8fd02f7c39..5bca15411f 100644
--- a/chrome/content/zotero/xpcom/dataDirectory.js
+++ b/chrome/content/zotero/xpcom/dataDirectory.js
@@ -86,7 +86,7 @@ Zotero.DataDirectory = {
 				dataDir = dir;
 			}
 		}
-		else if (Zotero.Prefs.get('useDataDir')) {
+		else if (Zotero.Prefs.get('useDataDir') && Zotero.Prefs.get('dataDir')) {
 			let prefVal = Zotero.Prefs.get('dataDir');
 			// Convert old persistent descriptor pref to string path and clear obsolete lastDataDir pref
 			//