diff --git a/chrome/content/zotero/xpcom/reader.js b/chrome/content/zotero/xpcom/reader.js
index 7d0636d47d..896bd7c8b8 100644
--- a/chrome/content/zotero/xpcom/reader.js
+++ b/chrome/content/zotero/xpcom/reader.js
@@ -798,6 +798,9 @@ class ReaderInstance {
 		let rect = this._iframe.getBoundingClientRect();
 		x += rect.left;
 		y += rect.top;
+		if (Zotero.rtl) {
+			x *= -1;
+		}
 		setTimeout(() => popup.openPopup(null, 'before_start', x, y, true));
 	}