diff --git a/ArbiterCommand.c b/ArbiterCommand.c
index b3a5966..47a1111 100644
--- a/ArbiterCommand.c
+++ b/ArbiterCommand.c
@@ -219,15 +219,15 @@ static _Noreturn void Serial_ToCanSpontany_Thread(tTaskSerialToCanSpontany *env)
                                                      1000);
                 if (sent) {
                     if (data.from_uart == FROM_UART) {
-                        env->ioUART->transmit(env->ioUART->env, (uint8_t *) "OK\r\n", sizeof("OK\r\n"), 1000);
+                        env->ioUART->transmit(env->ioUART->env, (uint8_t *) "OK\r\n", sizeof("OK\r\n") - 1, 1000);
                     } else {
-                        env->ioUSB->transmit(env->ioUSB->env, (uint8_t *) "OK\r\n", sizeof("OK\r\n"), 1000);
+                        env->ioUSB->transmit(env->ioUSB->env, (uint8_t *) "OK\r\n", sizeof("OK\r\n") - 1, 1000);
                     }
                 } else {
                     if (data.from_uart == FROM_UART) {
-                        env->ioUART->transmit(env->ioUART->env, (uint8_t *) "ERROR\r\n", sizeof("ERROR\r\n"), 1000);
+                        env->ioUART->transmit(env->ioUART->env, (uint8_t *) "ERROR\r\n", sizeof("ERROR\r\n") - 1, 1000);
                     } else {
-                        env->ioUSB->transmit(env->ioUSB->env, (uint8_t *) "ERROR\r\n", sizeof("ERROR\r\n"), 1000);
+                        env->ioUSB->transmit(env->ioUSB->env, (uint8_t *) "ERROR\r\n", sizeof("ERROR\r\n") - 1, 1000);
                     }
                 }
 
@@ -238,15 +238,15 @@ static _Noreturn void Serial_ToCanSpontany_Thread(tTaskSerialToCanSpontany *env)
 
                 if (sent) {
                     if (data.from_uart == FROM_UART) {
-                        env->ioUART->transmit(env->ioUART->env, (uint8_t *) "OK\r\n", sizeof("OK\r\n"), 1000);
+                        env->ioUART->transmit(env->ioUART->env, (uint8_t *) "OK\r\n", sizeof("OK\r\n") - 1, 1000);
                     } else {
                         env->ioUSB->transmit(env->ioUSB->env, (uint8_t *) "OK\r\n", sizeof("OK\r\n"), 1000);
                     }
                 } else {
                     if (data.from_uart == FROM_UART) {
-                        env->ioUART->transmit(env->ioUART->env, (uint8_t *) "ERROR\r\n", sizeof("ERROR\r\n"), 1000);
+                        env->ioUART->transmit(env->ioUART->env, (uint8_t *) "ERROR\r\n", sizeof("ERROR\r\n") - 1, 1000);
                     } else {
-                        env->ioUSB->transmit(env->ioUSB->env, (uint8_t *) "ERROR\r\n", sizeof("ERROR\r\n"), 1000);
+                        env->ioUSB->transmit(env->ioUSB->env, (uint8_t *) "ERROR\r\n", sizeof("ERROR\r\n") - 1, 1000);
                     }
                 }
 
@@ -392,8 +392,8 @@ void SerialCommand_Scheduler(tTaskSerial *env) {
         }
 
         if (AtCmdRxBeginWithStatic(&env->At, "V")) {
-            env->ioUART->transmit(env->ioUART->env, (uint8_t *) "v001\r\n", sizeof("v001\r\n"), 1000);
-            env->ioUART->transmit(env->ioUART->env, (uint8_t *) "OK\r\n", sizeof("OK\r\n"), 1000);
+            env->ioUART->transmit(env->ioUART->env, (uint8_t *) "v001\r\n", sizeof("v001\r\n") - 1, 1000);
+            env->ioUART->transmit(env->ioUART->env, (uint8_t *) "OK\r\n", sizeof("OK\r\n") - 1, 1000);
         }
     }