diff --git a/LUFA/Drivers/USB/Core/UC3/USBController_UC3.h b/LUFA/Drivers/USB/Core/UC3/USBController_UC3.h
index 4a5d267c82..006e089704 100644
--- a/LUFA/Drivers/USB/Core/UC3/USBController_UC3.h
+++ b/LUFA/Drivers/USB/Core/UC3/USBController_UC3.h
@@ -84,6 +84,16 @@
 			#error F_USB is not defined. You must define F_USB to the frequency of the clock input to the USB module.
 		#endif
 
+		#if (defined(USB_SERIES_UC3A3_AVR) || defined(USB_SERIES_UC3A4_AVR))
+			#if ((F_USB < 12000000) || (F_USB % 12000000))
+				#error Invalid F_USB specified. F_USB must be a multiple of 12MHz for UC3A3 and UC3A4 devices.
+			#endif		
+		#else
+			#if ((F_USB < 48000000) || (F_USB % 48000000))
+				#error Invalid F_USB specified. F_USB must be a multiple of 48MHz for UC3A and UC3B devices.
+			#endif		
+		#endif
+		
 	/* Public Interface - May be used in end-application: */
 		/* Macros: */
 			/** \name USB Controller Option Masks */
diff --git a/LUFA/Drivers/USB/Core/USBMode.h b/LUFA/Drivers/USB/Core/USBMode.h
index f62c8c152f..7ae30bbcd2 100644
--- a/LUFA/Drivers/USB/Core/USBMode.h
+++ b/LUFA/Drivers/USB/Core/USBMode.h
@@ -102,6 +102,11 @@
 		 */
 		#define USB_SERIES_UC3A3_AVR
 
+		/** Indicates that the target AVR microcontroller belongs to the AVR32 UC3A4 Series USB controller
+		 *  (i.e. AT32UC3A4*) when defined.
+		 */
+		#define USB_SERIES_UC3A4_AVR
+		
 		/** Indicates that the target AVR microcontroller belongs to the AVR32 UC3B0 Series USB controller
 		 *  (i.e. AT32UC3B0*) when defined.
 		 */