diff --git a/relay.py b/relay.py
index a1314ff..792ac93 100755
--- a/relay.py
+++ b/relay.py
@@ -165,14 +165,18 @@ scan_to_hid = {
 }
 
 
-LEFT_CTRL = 1 << 0
-LEFT_SHIFT = 1 << 1
-LEFT_ALT = 1 << 2
-LEFT_GUI = 1 << 3
-RIGHT_CTRL = 1 << 4
-RIGHT_SHIFT = 1 << 5
-RIGHT_ALT = 1 << 6
-RIGHT_GUI = 1 << 7
+modifiers = {
+    evdev.ecodes.KEY_LEFTCTRL: 1 << 0,
+    evdev.ecodes.KEY_LEFTSHIFT: 1 << 1,
+    evdev.ecodes.KEY_LEFTALT: 1 << 2,
+    evdev.ecodes.KEY_LEFTMETA: 1 << 3,
+
+    evdev.ecodes.KEY_RIGHTCTRL: 1 << 4,
+    evdev.ecodes.KEY_RIGHTSHIFT: 1 << 5,
+    evdev.ecodes.KEY_RIGHTALT: 1 << 6,
+    evdev.ecodes.KEY_RIGHTMETA: 1 << 7,
+}
+
 
 
 if __name__ == '__main__':
@@ -196,26 +200,31 @@ if __name__ == '__main__':
         data = evdev.categorize(event)
         print("Got key", data.scancode)
 
-
-
-        code = scan_to_hid.get(data.scancode, None)
-        if code is None:
-            print("Ignoring unknown key")
-            continue
-
-        if data.keystate == data.key_down:
-            if len(keys_down) >= 6:
-                print("Ignoring key due to rollover")
+        modifier = modifiers.get(data.scancode, None)
+        if modifier:
+            if data.keystate == data.key_down:
+                modifier_state |= modifier
+            if data.keystate == data.key_up:
+                modifier_state &= ~modifier
+        else:
+            code = scan_to_hid.get(data.scancode, None)
+            if code is None:
+                print("Ignoring unknown key")
                 continue
-            print("Adding key")
-            keys_down.add(code)
 
-        if data.keystate == data.key_up:
-            print("Removing key")
-            keys_down.remove(code)
+            if data.keystate == data.key_down:
+                if len(keys_down) >= 6:
+                    print("Ignoring key due to rollover")
+                    continue
+                print("Adding key")
+                keys_down.add(code)
+
+            if data.keystate == data.key_up:
+                print("Removing key")
+                keys_down.remove(code)
 
         # Build the packet
-        packet = [0] + [0] + [k for k in keys_down]
+        packet = [modifier_state, 0] + [k for k in keys_down]
         packet += [0] * (8 - len(packet))
 
         assert(len(packet) == 8)