diff --git a/CHANGELOG.md b/CHANGELOG.md
index 49c2059a..6419f939 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,13 @@ FlatLaf Change Log
 - ToolBar: Fixed endless loop if button in Toolbar has focus and is made
   invisible. (issue #884)
 
+#### Other Changes
+
+- Added system property `flatlaf.useRoundedPopupBorder` to allow disabling
+  native rounded popup borders on Windows 11 and macOS. On macOS 14.4+, where
+  rounded popup borders are disabled since FlatLaf 3.5 because of occasional
+  problems, you can use this to enable rounded popup borders (at your risk).
+
 
 ## 3.5.1
 
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatSystemProperties.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatSystemProperties.java
index 956c2b9e..b43082a4 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatSystemProperties.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/FlatSystemProperties.java
@@ -135,6 +135,17 @@ public interface FlatSystemProperties
 	 */
 	String ANIMATION = "flatlaf.animation";
 
+	/**
+	 * Specifies whether native rounded popup borders should be used (if supported by operating system).
+	 * <p>
+	 * (requires Window 11 or macOS)
+	 * <p>
+	 * <strong>Allowed Values</strong> {@code false} and {@code true}<br>
+	 * <strong>Default</strong> {@code true}; except on macOS 14.4+ where it is {@code false}
+	 * @since 3.5.2
+	 */
+	String USE_ROUNDED_POPUP_BORDER = "flatlaf.useRoundedPopupBorder";
+
 	/**
 	 * Specifies whether vertical text position is corrected when UI is scaled on HiDPI screens.
 	 * <p>
diff --git a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupFactory.java b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupFactory.java
index b4f5abad..94e7cda8 100644
--- a/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupFactory.java
+++ b/flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatPopupFactory.java
@@ -63,6 +63,7 @@ import javax.swing.border.EmptyBorder;
 import javax.swing.border.LineBorder;
 import javax.swing.plaf.basic.BasicComboPopup;
 import com.formdev.flatlaf.FlatClientProperties;
+import com.formdev.flatlaf.FlatSystemProperties;
 import com.formdev.flatlaf.util.SystemInfo;
 import com.formdev.flatlaf.util.UIScale;
 
@@ -116,13 +117,7 @@ public class FlatPopupFactory
 		// macOS and Linux adds drop shadow to heavy weight popups
 		if( SystemInfo.isMacOS || SystemInfo.isLinux ) {
 			NonFlashingPopup popup = new NonFlashingPopup( getPopupForScreenOfOwner( owner, contents, x, y, true ), owner, contents );
-			if( popup.popupWindow != null && SystemInfo.isMacOS &&
-					// do not use rounded border on macOS 14.4+ because it may freeze the application
-					// and crash the macOS WindowServer process (reports vary from Finder restarts to OS restarts)
-					// https://github.com/apache/netbeans/issues/7560#issuecomment-2226439215
-					// https://github.com/apache/netbeans/issues/6647#issuecomment-2070124442
-					SystemInfo.osVersion < SystemInfo.toVersion( 14, 4, 0, 0 ) &&
-					FlatNativeMacLibrary.isLoaded() )
+			if( popup.popupWindow != null && isMacOSBorderSupported() )
 				setupRoundedBorder( popup.popupWindow, owner, contents );
 			return popup;
 		}
@@ -363,7 +358,21 @@ public class FlatPopupFactory
 	//---- native rounded border ----------------------------------------------
 
 	private static boolean isWindows11BorderSupported() {
-		return SystemInfo.isWindows_11_orLater && FlatNativeWindowsLibrary.isLoaded();
+		return SystemInfo.isWindows_11_orLater &&
+			FlatSystemProperties.getBoolean( FlatSystemProperties.USE_ROUNDED_POPUP_BORDER, true ) &&
+			FlatNativeWindowsLibrary.isLoaded();
+	}
+
+	private static boolean isMacOSBorderSupported() {
+		// do not use rounded border on macOS 14.4+ because it may freeze the application
+		// and crash the macOS WindowServer process (reports vary from Finder restarts to OS restarts)
+		// https://github.com/apache/netbeans/issues/7560#issuecomment-2226439215
+		// https://github.com/apache/netbeans/issues/6647#issuecomment-2070124442
+		boolean isMacOS_14_4_orLater = (SystemInfo.osVersion >= SystemInfo.toVersion( 14, 4, 0, 0 ));
+
+		return SystemInfo.isMacOS &&
+			FlatSystemProperties.getBoolean( FlatSystemProperties.USE_ROUNDED_POPUP_BORDER, !isMacOS_14_4_orLater ) &&
+			FlatNativeMacLibrary.isLoaded();
 	}
 
 	private static void setupRoundedBorder( Window popupWindow, Component owner, Component contents ) {