diff --git a/indra/llwindow/llopenglview-objc.mm b/indra/llwindow/llopenglview-objc.mm
index 0bbc821ae96cf6d1628186977a468220dd33233c..0d4c3babc10e3606734781f98de7cfe5cf552527 100644
--- a/indra/llwindow/llopenglview-objc.mm
+++ b/indra/llwindow/llopenglview-objc.mm
@@ -481,7 +481,7 @@ attributedStringInfo getSegments(NSAttributedString *str)
 
 - (void)setMarkedText:(id)aString selectedRange:(NSRange)selectedRange replacementRange:(NSRange)replacementRange
 {
-    if ([aString class] == NSClassFromString(@"NSConcreteMutableAttributedString"))
+	if ([aString isKindOfClass:NSClassFromString(@"NSConcreteMutableAttributedString")])
     {
         if (mMarkedTextAllowed)
         {