diff --git a/src/Avalonia.Controls/Presenters/TextPresenter.cs b/src/Avalonia.Controls/Presenters/TextPresenter.cs
index bb54ac4a39..f9c55e1f3b 100644
--- a/src/Avalonia.Controls/Presenters/TextPresenter.cs
+++ b/src/Avalonia.Controls/Presenters/TextPresenter.cs
@@ -106,6 +106,11 @@ namespace Avalonia.Controls.Presenters
             {
                 var start = Math.Min(selectionStart, selectionEnd);
                 var length = Math.Max(selectionStart, selectionEnd) - start;
+
+                // issue #600: set constaint before any FormattedText manipulation
+                //             see base.Render(...) implementation
+                FormattedText.Constraint = Bounds.Size;
+
                 var rects = FormattedText.HitTestTextRange(start, length);
 
                 if (_highlightBrush == null)