diff --git a/source/portable/NetworkInterface/Zynq/x_emacpsif.h b/source/portable/NetworkInterface/Zynq/x_emacpsif.h
index cd18fd997e..ba6836148b 100644
--- a/source/portable/NetworkInterface/Zynq/x_emacpsif.h
+++ b/source/portable/NetworkInterface/Zynq/x_emacpsif.h
@@ -60,7 +60,6 @@
 
     extern XEmacPs_Config mac_configs[ XPAR_XEMACPS_NUM_INSTANCES ];
 
-
     void xemacpsif_setmac( uint32_t index,
                            uint8_t * addr );
     uint8_t * xemacpsif_getmac( uint32_t index );
@@ -115,7 +114,8 @@
         volatile int rxHead, rxTail;
         volatile int txHead, txTail;
 
-        volatile int txBusy;
+        /* txMutex is replacing the earlier int variable 'txBusy'. */
+        SemaphoreHandle_t txMutex;
 
         volatile uint32_t isr_events;
 
diff --git a/source/portable/NetworkInterface/Zynq/x_emacpsif_dma.c b/source/portable/NetworkInterface/Zynq/x_emacpsif_dma.c
index a9b9e2b03d..66e7d702a6 100644
--- a/source/portable/NetworkInterface/Zynq/x_emacpsif_dma.c
+++ b/source/portable/NetworkInterface/Zynq/x_emacpsif_dma.c
@@ -221,7 +221,9 @@ void emacps_send_handler( void * arg )
      * "isr_events". The task in NetworkInterface will wake-up and do the necessary work.
      */
     xemacpsif->isr_events |= EMAC_IF_TX_EVENT;
-    xemacpsif->txBusy = pdFALSE;
+
+    /* Give to the mutex so that a new packet can be sent from emacps_send_message(). */
+    xSemaphoreGiveFromISR( xemacpsif->txMutex, &xHigherPriorityTaskWoken );
 
     if( xEMACTaskHandles[ xEMACIndex ] != NULL )
     {
@@ -252,7 +254,6 @@ XStatus emacps_send_message( xemacpsif_s * xemacpsif,
                              int iReleaseAfterSend )
 {
     int txHead = xemacpsif->txHead;
-    int iHasSent = 0;
     uint32_t ulBaseAddress = xemacpsif->emacps.Config.BaseAddress;
     BaseType_t xEMACIndex = get_xEMACIndex( &xemacpsif->emacps );
     TickType_t xBlockTimeTicks = pdMS_TO_TICKS( 5000U );
@@ -315,8 +316,6 @@ XStatus emacps_send_message( xemacpsif_s * xemacpsif,
         {
         }
 
-        iHasSent = pdTRUE;
-
         txHead++;
 
         if( txHead == ipconfigNIC_N_TX_DESC )
@@ -328,18 +327,24 @@ XStatus emacps_send_message( xemacpsif_s * xemacpsif,
          * accessed as little as possible. */
         xemacpsif->txHead = txHead;
 
+        if( xSemaphoreTake( xemacpsif->txMutex, 200U ) == pdFALSE )
+        {
+            FreeRTOS_printf( ( "emacps_send_message: mutex can not be taken, something is really wrong.\n" ) );
+            /* There is no risk in continuing here. */
+        }
+
         /* Data Synchronization Barrier */
         dsb();
 
-        if( iHasSent == pdTRUE )
         {
             /* Make STARTTX high */
             uint32_t ulValue = XEmacPs_ReadReg( ulBaseAddress, XEMACPS_NWCTRL_OFFSET );
-            /* Start transmit */
-            xemacpsif->txBusy = pdTRUE;
-            XEmacPs_WriteReg( ulBaseAddress, XEMACPS_NWCTRL_OFFSET, ( ulValue | XEMACPS_NWCTRL_STARTTX_MASK ) );
+            /* Set the Start transmit bit. */
+            ulValue |= XEMACPS_NWCTRL_STARTTX_MASK;
+            XEmacPs_WriteReg( ulBaseAddress, XEMACPS_NWCTRL_OFFSET, ulValue );
             /* Read back the register to make sure the data is flushed. */
             ( void ) XEmacPs_ReadReg( ulBaseAddress, XEMACPS_NWCTRL_OFFSET );
+            /* The mutex will be given later on in emacps_send_handler(). */
         }
 
         dsb();
@@ -685,6 +690,15 @@ XStatus init_dma( xemacpsif_s * xemacpsif )
         configASSERT( xTXDescriptorSemaphores[ xEMACIndex ] );
     }
 
+    if( xemacpsif->txMutex == NULL )
+    {
+        /* txMutex can always be taken, except between sending a packet
+         * and receiving the TX RX interrupt. */
+        xemacpsif->txMutex = xSemaphoreCreateBinary();
+        configASSERT( xemacpsif->txMutex != NULL );
+        xSemaphoreGive( xemacpsif->txMutex );
+    }
+
     /*
      * Allocate RX descriptors, 1 RxBD at a time.
      */