diff --git a/flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatTestFrame.java b/flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatTestFrame.java
index 87ef3afc..3d25767e 100644
--- a/flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatTestFrame.java
+++ b/flatlaf-testing/src/main/java/com/formdev/flatlaf/testing/FlatTestFrame.java
@@ -229,7 +229,7 @@ public class FlatTestFrame
 
 	private boolean isClassAvailable( String className ) {
 		try {
-			Class.forName( className );
+			Class.forName( className, false, getClass().getClassLoader() );
 			return true;
 		} catch( ClassNotFoundException ex ) {
 			return false;