diff --git a/src/Windows/Avalonia.Win32/WindowImpl.cs b/src/Windows/Avalonia.Win32/WindowImpl.cs
index acf9bd72d2f..ffd9b08d4a1 100644
--- a/src/Windows/Avalonia.Win32/WindowImpl.cs
+++ b/src/Windows/Avalonia.Win32/WindowImpl.cs
@@ -1348,7 +1348,7 @@ private void UpdateWindowProperties(WindowProperties newProperties, bool forceCh
                 {
                     style &= ~fullDecorationFlags;
 
-                    if (newProperties.Decorations == SystemDecorations.BorderOnly)
+                    if (newProperties.Decorations == SystemDecorations.BorderOnly && WindowState != WindowState.Maximized)
                     {
                         style |= WindowStyles.WS_THICKFRAME | WindowStyles.WS_BORDER;
                     }