diff --git a/right/src/keyboard_layout.c b/right/src/keyboard_layout.c
new file mode 100644
index 0000000..6f5f5ee
--- /dev/null
+++ b/right/src/keyboard_layout.c
@@ -0,0 +1,83 @@
+#include "keyboard_layout.h"
+
+static uint8_t keyMasks[LAYOUT_KEY_COUNT];
+
+static inline __attribute__((always_inline)) uint8_t getKeycode(KEYBOARD_LAYOUT(layout), uint8_t keyId, uint8_t modifierState)
+{
+	if (keyId<LAYOUT_KEY_COUNT) {
+		if (keyMasks[keyId]!=0 && keyMasks[keyId]!=modifierState){
+			//Mask out key presses after releasing modifier keys
+			return 0;
+		}
+
+		uint8_t k = layout[keyId][modifierState];
+		keyMasks[keyId] = modifierState;
+
+		if (k==0) {
+			k = layout[keyId][0];
+		}
+
+		return k;
+	} else {
+		return 0;
+	}
+}
+
+
+static uint8_t getModifierState(const uint8_t *leftKeyStates, const uint8_t *rightKeyStates){
+	uint8_t mod = 0;
+	if (leftKeyStates[KEYID_LEFT_MOD]) {
+		mod |= MODIFIER_MOD_PRESSED;
+	}
+	if (leftKeyStates[KEYID_LEFT_FN] | rightKeyStates[KEYID_RIGHT_FN]) {
+		mod |= MODIFIER_FN_PRESSED;
+	}
+
+	return mod;
+}
+
+static void clearKeymasks(const uint8_t *leftKeyStates, const uint8_t *rightKeyStates){
+	int i;
+	for (i=0; i<KEY_STATE_COUNT; ++i){
+		if (rightKeyStates[i]==0){
+			keyMasks[i] = 0;
+		}
+
+		if (leftKeyStates[i]==0){
+			keyMasks[LAYOUT_LEFT_OFFSET+i] = 0;
+		}
+	}
+}
+
+void fillKeyboardReport(usb_keyboard_report_t *report, const uint8_t *leftKeyStates, const uint8_t *rightKeyStates, KEYBOARD_LAYOUT(layout)){
+	int scancodeIdx = 0;
+
+	clearKeymasks(leftKeyStates, rightKeyStates);
+	uint8_t modifierState=getModifierState(leftKeyStates, rightKeyStates);
+
+	for (uint8_t keyId=0; keyId<KEY_STATE_COUNT; keyId++) {
+		if (scancodeIdx>=USB_KEYBOARD_MAX_KEYS) {
+			break;
+		}
+
+		if (rightKeyStates[keyId]) {
+			uint8_t code=getKeycode(layout, keyId, modifierState);
+			if (code) {
+				report->scancodes[scancodeIdx++] = code;
+			}
+		}
+	}
+
+	for (uint8_t keyId=0; keyId<KEY_STATE_COUNT; keyId++) {
+		if (scancodeIdx>=USB_KEYBOARD_MAX_KEYS) {
+			break;
+		}
+
+		if (leftKeyStates[keyId]) {
+			uint8_t code=getKeycode(layout, LAYOUT_LEFT_OFFSET+keyId, modifierState);
+			if (code) {
+				report->scancodes[scancodeIdx++] = code;
+			}
+		}
+	}
+}
diff --git a/right/src/keyboard_layout.h b/right/src/keyboard_layout.h
index 881ac0e..91a2ffe 100644
--- a/right/src/keyboard_layout.h
+++ b/right/src/keyboard_layout.h
@@ -3,6 +3,7 @@
 
 #include <stdint.h>
 #include "lufa/HIDClassCommon.h"
+#include "usb_composite_device.h"
 
 /**
  * Keyboard layout is a 2D array of scan codes.
@@ -35,31 +36,6 @@
 #define MODIFIER_MOD_PRESSED 1
 #define MODIFIER_FN_PRESSED 2
 
-
-static inline __attribute__((always_inline)) uint8_t getKeycode(KEYBOARD_LAYOUT(layout), uint8_t keyId, uint8_t modifierState)
-{
-	if (keyId<LAYOUT_KEY_COUNT) {
-		uint8_t k = layout[keyId][modifierState];
-		if (k==0) {
-			k = layout[keyId][0];
-		}
-
-		return k;
-	} else {
-		return 0;
-	}
-}
-
-static inline __attribute__((always_inline)) uint8_t getModifierState(const uint8_t *leftKeyStates, const uint8_t *rightKeyStates){
-	uint8_t mod = 0;
-	if (leftKeyStates[KEYID_LEFT_MOD]) {
-		mod |= MODIFIER_MOD_PRESSED;
-	}
-	if (leftKeyStates[KEYID_LEFT_FN] | rightKeyStates[KEYID_RIGHT_FN]) {
-		mod |= MODIFIER_FN_PRESSED;
-	}
-
-	return mod;
-}
+void fillKeyboardReport(usb_keyboard_report_t *report, const uint8_t *leftKeyStates, const uint8_t *rightKeyStates, KEYBOARD_LAYOUT(layout));
 
 #endif
diff --git a/right/src/usb_interface_keyboard.c b/right/src/usb_interface_keyboard.c
index a87745f..8878a4a 100644
--- a/right/src/usb_interface_keyboard.c
+++ b/right/src/usb_interface_keyboard.c
@@ -41,7 +41,7 @@ usb_device_class_struct_t UsbKeyboardClass = {
 };
 
 volatile static int activeLayout=0;
-volatile static usb_keyboard_report_t UsbKeyboardReport[2];
+static usb_keyboard_report_t UsbKeyboardReport[2];
 
 #define KEYBOARD_MATRIX_COLS_NUM 7
 #define KEYBOARD_MATRIX_ROWS_NUM 5
@@ -100,34 +100,7 @@ void usbKeyboadTask(){
 
 	readLeftKeys(leftKeyStates);
 
-	uint8_t modifierState = getModifierState(leftKeyStates, keyMatrix.keyStates);
-
-	int scancodeIdx = 0;
-	for (uint8_t keyId=0; keyId<KEYBOARD_MATRIX_COLS_NUM*KEYBOARD_MATRIX_ROWS_NUM; keyId++) {
-		if (scancodeIdx>=USB_KEYBOARD_MAX_KEYS) {
-			break;
-		}
-
-		if (keyMatrix.keyStates[keyId]) {
-			uint8_t code=getKeycode(defaultKeyboardLayout, keyId, modifierState);
-			if (code) {
-				UsbKeyboardReport[newLayout].scancodes[scancodeIdx++] = code;
-			}
-		}
-	}
-
-	for (uint8_t keyId=0; keyId<KEY_STATE_COUNT; keyId++) {
-		if (scancodeIdx>=USB_KEYBOARD_MAX_KEYS) {
-			break;
-		}
-
-		if (leftKeyStates[keyId]) {
-			uint8_t code=getKeycode(defaultKeyboardLayout, LAYOUT_LEFT_OFFSET+keyId, modifierState);
-			if (code) {
-				UsbKeyboardReport[newLayout].scancodes[scancodeIdx++] = code;
-			}
-		}
-	}
+	fillKeyboardReport(&UsbKeyboardReport[newLayout], leftKeyStates, keyMatrix.keyStates, defaultKeyboardLayout);
 
 	//Change to the new layout in atomic operation (int copy). Even if
 	//the copy is not atomic itself, only single bit changes. So it can