diff --git a/Bootloaders/CDC/BootloaderCDC.h b/Bootloaders/CDC/BootloaderCDC.h
index b5d5e0b028..76d579d269 100644
--- a/Bootloaders/CDC/BootloaderCDC.h
+++ b/Bootloaders/CDC/BootloaderCDC.h
@@ -52,6 +52,11 @@
 		#include <LUFA/Drivers/USB/USB.h>
 		#include <LUFA/Drivers/Board/LEDs.h>
 
+	/* Preprocessor Checks: */
+		#if !defined(__OPTIMIZE_SIZE__)
+			#error This bootloader requires that it be compiled for size, not speed for it to fit into the target device.
+		#endif
+
 	/* Macros: */
 		/** Version major of the CDC bootloader. */
 		#define BOOTLOADER_VERSION_MAJOR     0x01
diff --git a/Bootloaders/DFU/BootloaderDFU.h b/Bootloaders/DFU/BootloaderDFU.h
index 5223e47eb0..537902393b 100644
--- a/Bootloaders/DFU/BootloaderDFU.h
+++ b/Bootloaders/DFU/BootloaderDFU.h
@@ -54,13 +54,18 @@
 		#include <LUFA/Drivers/USB/USB.h>
 		#include <LUFA/Drivers/Board/LEDs.h>
 
+	/* Preprocessor Checks: */
+		#if !defined(__OPTIMIZE_SIZE__)
+			#error This bootloader requires that it be compiled for size, not speed for it to fit into the target device.
+		#endif
+
 	/* Macros: */
 		/** Major bootloader version number. */
 		#define BOOTLOADER_VERSION_MINOR 2
 
 		/** Minor bootloader version number. */
 		#define BOOTLOADER_VERSION_REV   0
-		
+
 		/** Magic bootloader key to unlock forced application start mode. */
 		#define MAGIC_BOOT_KEY            0xDC42
 
@@ -203,7 +208,7 @@
 			static void ProcessWriteCommand(void);
 			static void ProcessReadCommand(void);
 		#endif
-		
+
 		void Application_Jump_Check(void) ATTR_INIT_SECTION(3);
 
 #endif
diff --git a/Bootloaders/HID/BootloaderHID.h b/Bootloaders/HID/BootloaderHID.h
index 306f3efa9f..e63b19d947 100644
--- a/Bootloaders/HID/BootloaderHID.h
+++ b/Bootloaders/HID/BootloaderHID.h
@@ -48,18 +48,23 @@
 
 		#include <LUFA/Drivers/USB/USB.h>
 
+	/* Preprocessor Checks: */
+		#if !defined(__OPTIMIZE_SIZE__)
+			#error This bootloader requires that it be compiled for size, not speed for it to fit into the target device.
+		#endif
+
 	/* Macros: */
 		/** Bootloader special address to start the user application */
 		#define COMMAND_STARTAPPLICATION   0xFFFF
 
 		/** Magic bootloader key to unlock forced application start mode. */
 		#define MAGIC_BOOT_KEY             0xDC42
-		
+
 	/* Function Prototypes: */
 		static void SetupHardware(void);
 
 		void Application_Jump_Check(void) ATTR_INIT_SECTION(3);
-		
+
 		void EVENT_USB_Device_ConfigurationChanged(void);
 		void EVENT_USB_Device_UnhandledControlRequest(void);
 
diff --git a/Bootloaders/MassStorage/BootloaderMassStorage.h b/Bootloaders/MassStorage/BootloaderMassStorage.h
index 05b0eedfec..5e90739ad4 100644
--- a/Bootloaders/MassStorage/BootloaderMassStorage.h
+++ b/Bootloaders/MassStorage/BootloaderMassStorage.h
@@ -50,6 +50,11 @@
 		#include <LUFA/Drivers/Board/LEDs.h>
 		#include <LUFA/Drivers/USB/USB.h>
 
+	/* Preprocessor Checks: */
+		#if !defined(__OPTIMIZE_SIZE__)
+			#error This bootloader requires that it be compiled for size, not speed for it to fit into the target device.
+		#endif
+
 	/* Macros: */
 		/** LED mask for the library LED driver, to indicate that the USB interface is not ready. */
 		#define LEDMASK_USB_NOTREADY      LEDS_LED1
diff --git a/Bootloaders/Printer/BootloaderPrinter.h b/Bootloaders/Printer/BootloaderPrinter.h
index 4995cdca9f..22104c53f0 100644
--- a/Bootloaders/Printer/BootloaderPrinter.h
+++ b/Bootloaders/Printer/BootloaderPrinter.h
@@ -47,6 +47,11 @@
 		#include <LUFA/Drivers/USB/USB.h>
 		#include <LUFA/Drivers/Board/LEDs.h>
 
+	/* Preprocessor Checks: */
+		#if !defined(__OPTIMIZE_SIZE__)
+			#error This bootloader requires that it be compiled for size, not speed for it to fit into the target device.
+		#endif
+
 	/* Macros: */
 		/** LED mask for the library LED driver, to indicate that the USB interface is not ready. */
 		#define LEDMASK_USB_NOTREADY       LEDS_LED1