diff --git a/hardware/AFSK.c b/hardware/AFSK.c
index 50a5214..00a57ed 100755
--- a/hardware/AFSK.c
+++ b/hardware/AFSK.c
@@ -84,6 +84,7 @@ static void AFSK_txStart(Afsk *afsk) {
         afsk->phaseAcc = 0;
         afsk->bitstuffCount = 0;
         afsk->sending = true;
+        afsk->sending_data = true;
         LED_TX_ON();
         afsk->preambleLength = DIV_ROUND(custom_preamble * BITRATE, 8000);
         AFSK_DAC_IRQ_START();
@@ -121,6 +122,7 @@ uint8_t AFSK_dac_isr(Afsk *afsk) {
             if (fifo_isempty(&afsk->txFifo) && afsk->tailLength == 0) {
                 AFSK_DAC_IRQ_STOP();
                 afsk->sending = false;
+                afsk->sending_data = false;
                 LED_TX_OFF();
                 return 0;
             } else {
@@ -128,6 +130,7 @@ uint8_t AFSK_dac_isr(Afsk *afsk) {
                 afsk->bitStuff = true;
                 if (afsk->preambleLength == 0) {
                     if (fifo_isempty(&afsk->txFifo)) {
+                        afsk->sending_data = false;
                         afsk->tailLength--;
                         afsk->currentOutputByte = HDLC_FLAG;
                     } else {
diff --git a/hardware/AFSK.h b/hardware/AFSK.h
index be69381..e171fd8 100755
--- a/hardware/AFSK.h
+++ b/hardware/AFSK.h
@@ -104,9 +104,10 @@ typedef struct Afsk
     uint16_t phaseInc;                      // Phase increment per sample
 
     FIFOBuffer txFifo;                      // FIFO for transmit data
-    uint8_t txBuf[CONFIG_AFSK_TX_BUFLEN];   // Actial data storage for said FIFO
+    uint8_t txBuf[CONFIG_AFSK_TX_BUFLEN];   // Actual data storage for said FIFO
 
     volatile bool sending;                  // Set when modem is sending
+    volatile bool sending_data;             // Set when modem is sending data
 
     // Demodulation values
     FIFOBuffer delayFifo;                   // Delayed FIFO for frequency discrimination
diff --git a/protocol/AX25.c b/protocol/AX25.c
index d488ea6..f291ecb 100755
--- a/protocol/AX25.c
+++ b/protocol/AX25.c
@@ -114,6 +114,7 @@ void ax25_sendRaw(AX25Ctx *ctx, void *_buf, size_t len) {
     ax25_putchar(ctx, crch);
 
     fputc(HDLC_FLAG, ctx->ch);
+
 }
 
 #if SERIAL_PROTOCOL == PROTOCOL_SIMPLE_SERIAL
diff --git a/protocol/KISS.c b/protocol/KISS.c
index 441c534..0c6e967 100755
--- a/protocol/KISS.c
+++ b/protocol/KISS.c
@@ -11,6 +11,7 @@ Serial *serial;
 size_t frame_len;
 bool IN_FRAME;
 bool ESCAPE;
+bool FLOWCONTROL;
 
 uint8_t command = CMD_UNKNOWN;
 unsigned long custom_preamble = CONFIG_AFSK_PREAMBLE_LEN;
@@ -23,6 +24,7 @@ void kiss_init(AX25Ctx *ax25, Afsk *afsk, Serial *ser) {
     ax25ctx = ax25;
     serial = ser;
     channel = afsk;
+    FLOWCONTROL = false;
 }
 
 void kiss_messageCallback(AX25Ctx *ctx) {
@@ -75,9 +77,16 @@ void kiss_csma(AX25Ctx *ctx, uint8_t *buf, size_t len) {
                 }
             }
         }
-
     }
-    
+
+    if (FLOWCONTROL) {
+        while (channel->sending_data) { /* Wait */ }
+
+        fputc(FEND, &serial->uart0);
+        fputc(CMD_READY, &serial->uart0);
+        fputc(0x01, &serial->uart0);
+        fputc(FEND, &serial->uart0);
+    }
 }
 
 void kiss_serialCallback(uint8_t sbyte) {
@@ -114,7 +123,13 @@ void kiss_serialCallback(uint8_t sbyte) {
             slotTime = sbyte * 10;
         } else if (command == CMD_P) {
             p = sbyte;
-        } 
+        } else if (command == CMD_READY) {
+            if (sbyte == 0x00) {
+                FLOWCONTROL = false;
+            } else {
+                FLOWCONTROL = true;
+            }
+        }
         
     }
 }
\ No newline at end of file
diff --git a/protocol/KISS.h b/protocol/KISS.h
index f39a11b..b762772 100755
--- a/protocol/KISS.h
+++ b/protocol/KISS.h
@@ -19,6 +19,7 @@
 #define CMD_TXTAIL 0x04
 #define CMD_FULLDUPLEX 0x05
 #define CMD_SETHARDWARE 0x06
+#define CMD_READY 0x0F
 #define CMD_RETURN 0xFF
 
 void kiss_init(AX25Ctx *ax25, Afsk *afsk, Serial *ser);