diff --git a/C64_4joy_adapter/4joy_adapter.ino b/C64_4joy_adapter/4joy_adapter.ino
index b3ef918..fad2905 100644
--- a/C64_4joy_adapter/4joy_adapter.ino
+++ b/C64_4joy_adapter/4joy_adapter.ino
@@ -121,7 +121,7 @@ void loop() {
 
   GPIOR0 = joy1; GPIOR1 = joy2;
 
-  PORTB = *ptr; // is this atomic? probably, because ptr is 6-bit pointer?
+  PORTB = *ptr; // is this atomic? probably, because ptr is 6-bit pointer.
   //delayMicroseconds(10);
   //uint16_t koe = ptr;
   //Serial.println(koe, HEX);