diff --git a/src/wp-includes/js/quicktags.js b/src/wp-includes/js/quicktags.js
index 11f8785059..6d00901a78 100644
--- a/src/wp-includes/js/quicktags.js
+++ b/src/wp-includes/js/quicktags.js
@@ -526,6 +526,11 @@ function edButton(id, display, tagStart, tagEnd, access) {
 		} else if ( canvas.selectionStart || canvas.selectionStart === 0 ) { // FF, WebKit, Opera
 			startPos = canvas.selectionStart;
 			endPos = canvas.selectionEnd;
+
+			if ( startPos < endPos && v.charAt( endPos - 1 ) === '\n' ) {
+				endPos -= 1;
+			}
+
 			cursorPos = endPos;
 			scrollTop = canvas.scrollTop;
 			l = v.substring(0, startPos); // left of the selection