diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatButtonUI.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatButtonUI.java
index c9152d76..6055b3bd 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatButtonUI.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatButtonUI.java
@@ -399,6 +399,8 @@ public class FlatButtonUI
 			return new Dimension( helpButtonIcon.getIconWidth(), helpButtonIcon.getIconHeight() );
 
 		Dimension prefSize = super.getPreferredSize( c );
+		if ( prefSize == null )
+			return null;
 
 		// make button square if it is a icon-only button
 		// or apply minimum width, if not in toolbar and not a icon-only button