diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5e138e9..971c427 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -53,7 +53,6 @@ set(TARGET_SOURCES
     "SDK/devices/MK60D10/system_MK60D10.c"
     "SDK/devices/MK60D10/utilities/fsl_debug_console.c"
     "SDK/devices/MK60D10/utilities/fsl_notifier.c"
-    "SDK/devices/MK60D10/utilities/fsl_sbrk.c"
     "SDK/devices/MK60D10/gcc/startup_MK60D10.S"
     "SDK/devices/MK60D10/system_MK60D10.c"
     "board/board.c"
@@ -74,6 +73,8 @@ set(TARGET_SOURCES
 set(TARGET_C_DEFINES
     "CPU_MK60DN512VLQ10"
     "__STARTUP_CLEAR_BSS"
+    "USE_RTOS=1"
+    "FSL_RTOS_FREE_RTOS"
 )
 
 set(TARGET_C_INCLUDES
diff --git a/MK60DN512xxx10_flash_sram.ld b/MK60DN512xxx10_flash_sram.ld
index facb34d..58e9af1 100644
--- a/MK60DN512xxx10_flash_sram.ld
+++ b/MK60DN512xxx10_flash_sram.ld
@@ -49,7 +49,7 @@
 /* Entry Point */
 ENTRY(Reset_Handler)
 
-HEAP_SIZE  = DEFINED(__heap_size__)  ? __heap_size__  : 0x0400;
+HEAP_SIZE  = DEFINED(__heap_size__)  ? __heap_size__  : 0x1000;
 STACK_SIZE = DEFINED(__stack_size__) ? __stack_size__ : 0x0400;
 M_VECTOR_RAM_SIZE = DEFINED(__ram_vector_table__) ? 0x0400 : 0x0;
 
diff --git a/include/FreeRTOSConfig.h b/include/FreeRTOSConfig.h
index 102101b..6e0409c 100644
--- a/include/FreeRTOSConfig.h
+++ b/include/FreeRTOSConfig.h
@@ -12,7 +12,7 @@
 #define configUSE_TICKLESS_IDLE                 0
 #define configCPU_CLOCK_HZ                      (SystemCoreClock)
 #define configTICK_RATE_HZ                      1000
-#define configMAX_PRIORITIES                    56
+#define configMAX_PRIORITIES                    64
 #define configMINIMAL_STACK_SIZE                128
 #define configMAX_TASK_NAME_LEN                 16
 #define configUSE_16_BIT_TICKS                  0
@@ -26,7 +26,7 @@
 #define configQUEUE_REGISTRY_SIZE               10
 #define configUSE_QUEUE_SETS                    0
 #define configUSE_TIME_SLICING                  0
-#define configUSE_NEWLIB_REENTRANT              0
+#define configUSE_NEWLIB_REENTRANT              1
 #define configENABLE_BACKWARD_COMPATIBILITY     0
 #define configNUM_THREAD_LOCAL_STORAGE_POINTERS 5
 #define configSTACK_DEPTH_TYPE                  uint16_t
@@ -57,7 +57,7 @@
 
 /* Software timer related definitions. */
 #define configUSE_TIMERS                        1
-#define configTIMER_TASK_PRIORITY               3
+#define configTIMER_TASK_PRIORITY               54
 #define configTIMER_QUEUE_LENGTH                10
 #define configTIMER_TASK_STACK_DEPTH            configMINIMAL_STACK_SIZE
 
diff --git a/lib/LwIP/port/include/lwipopts.h b/lib/LwIP/port/include/lwipopts.h
index 19760a2..291270b 100644
--- a/lib/LwIP/port/include/lwipopts.h
+++ b/lib/LwIP/port/include/lwipopts.h
@@ -90,7 +90,7 @@
 #define TCPIP_DEBUG                LWIP_DBG_OFF
 #define NETIF_DEBUG                LWIP_DBG_OFF
 #define SOCKETS_DEBUG              LWIP_DBG_OFF
-#define DNS_DEBUG                  LWIP_DBG_ON
+#define DNS_DEBUG                  LWIP_DBG_OFF
 #define AUTOIP_DEBUG               LWIP_DBG_OFF
 #define DHCP_DEBUG                 LWIP_DBG_ON
 #define IP_DEBUG                   LWIP_DBG_OFF
@@ -328,6 +328,7 @@ void lwip_platform_assert(const char *msg, int line, const char *file);
 #endif
 
 /* FreeRTOS related settings */
+#define TCPIP_THREAD_PRIO          47
 #define TCPIP_MBOX_SIZE            32
 #define TCPIP_THREAD_STACKSIZE     1024
 
diff --git a/src/ethernetif.c b/src/ethernetif.c
index a3dc367..a00391c 100644
--- a/src/ethernetif.c
+++ b/src/ethernetif.c
@@ -364,7 +364,7 @@ static void enet_init(struct netif *netif, struct ethernetif *ethernetif)
     ENET_Init(ethernetif->base, &ethernetif->handle, &config, &buffCfg, netif->hwaddr, sysClock);
 
 #if USE_RTOS && defined(FSL_RTOS_FREE_RTOS)
-    xTaskCreate(enet_rx_task, "enet_rx_task", 1024, netif, 2, &ethernetif->rxTaskHandle);
+    xTaskCreate(enet_rx_task, "enet_rx_task", 1024, netif, 48, &ethernetif->rxTaskHandle);
 
     ENET_SetCallback(&ethernetif->handle, ethernet_callback, netif);
 #endif
diff --git a/src/ip_stack_helpers.c b/src/ip_stack_helpers.c
index 3490f21..fd5c181 100644
--- a/src/ip_stack_helpers.c
+++ b/src/ip_stack_helpers.c
@@ -1,3 +1,5 @@
+#include <stdio.h>
+
 /* FreeRTOS */
 #include "FreeRTOS.h"
 #include "task.h"
@@ -21,7 +23,7 @@
 #define NTP_POOL_ADDR  "cn.pool.ntp.org"
 #define NETIF_HOSTNAME "k60_server"
 
-static char *s_netif_hostname = NETIF_HOSTNAME;
+static char        *s_netif_hostname = NETIF_HOSTNAME;
 static struct netif fsl_netif0;
 
 /* Report state => string */
@@ -43,25 +45,25 @@ static const char *report_type_str[] = {
 static void ip_stack_lwiperf_report(void *arg, enum lwiperf_report_type report_type, const ip_addr_t *local_addr,
                                     u16_t local_port, const ip_addr_t *remote_addr, u16_t remote_port,
                                     u32_t bytes_transferred, u32_t ms_duration, u32_t bandwidth_kbitpsec) {
-    PRINTF("-------------------------------------------------\r\n");
+    printf("-------------------------------------------------\r\n");
     if ((report_type < sizeof(report_type_str)) && local_addr && remote_addr) {
-        PRINTF(" %s \r\n", report_type_str[report_type]);
-        PRINTF(" Local address : %u.%u.%u.%u ", ((u8_t *)local_addr)[0], ((u8_t *)local_addr)[1],
+        printf(" %s \r\n", report_type_str[report_type]);
+        printf(" Local address : %u.%u.%u.%u ", ((u8_t *)local_addr)[0], ((u8_t *)local_addr)[1],
                ((u8_t *)local_addr)[2], ((u8_t *)local_addr)[3]);
-        PRINTF(" Port %d \r\n", local_port);
-        PRINTF(" Remote address : %u.%u.%u.%u ", ((u8_t *)remote_addr)[0], ((u8_t *)remote_addr)[1],
+        printf(" Port %d \r\n", local_port);
+        printf(" Remote address : %u.%u.%u.%u ", ((u8_t *)remote_addr)[0], ((u8_t *)remote_addr)[1],
                ((u8_t *)remote_addr)[2], ((u8_t *)remote_addr)[3]);
-        PRINTF(" Port %d \r\n", remote_port);
-        PRINTF(" Bytes Transferred %d \r\n", bytes_transferred);
-        PRINTF(" Duration (ms) %d \r\n", ms_duration);
-        PRINTF(" Bandwidth (kbitpsec) %d \r\n", bandwidth_kbitpsec);
+        printf(" Port %d \r\n", remote_port);
+        printf(" Bytes Transferred %ld \r\n", bytes_transferred);
+        printf(" Duration (ms) %ld \r\n", ms_duration);
+        printf(" Bandwidth (kbitpsec) %ld \r\n", bandwidth_kbitpsec);
     } else {
-        PRINTF(" IPERF Report error\r\n");
+        printf(" IPERF Report error\r\n");
     }
 }
 
 static void ip_stack_sntp_address_found(const char *name, const ip_addr_t *ipaddr, void *callback_arg) {
-    PRINTF("Resolved IP: %s\r\n", ipaddr_ntoa(ipaddr));
+    printf("Resolved IP: %s\r\n", ipaddr_ntoa(ipaddr));
     sntp_setserver(0, ipaddr);
     sntp_init();
 }
@@ -77,7 +79,7 @@ static void ip_stack_enable_sntp(void) {
         sntp_setserver(0, &ntp_addr);
         sntp_init();
     } else {
-        PRINTF("No cached DNS result found, wait for callback.\r\n");
+        printf("No cached DNS result found, wait for callback.\r\n");
     }
 }
 
@@ -103,7 +105,7 @@ void ip_stack_setup(void) {
         vTaskDelay(pdMS_TO_TICKS(500));
     }
 
-    PRINTF("IP Address: %s\r\n", ipaddr_ntoa(&fsl_netif0.ip_addr));
+    printf("IP Address: %s\r\n", ipaddr_ntoa(&fsl_netif0.ip_addr));
 
     ip_stack_enable_sntp();
 
diff --git a/src/main.c b/src/main.c
index 0a2abd8..72481d3 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,3 +1,4 @@
+#include <stdio.h>
 #include <time.h>
 
 /* HW Related */
@@ -49,7 +50,7 @@ static void vTaskHello(void *pvParameters) {
         t      = time(NULL);
         cur_tm = localtime(&t);
 
-        PRINTF("Current time: %04d-%02d-%02d %02d:%02d:%02d\r\n", cur_tm->tm_year + 1900, cur_tm->tm_mon + 1,
+        printf("Current time: %04d-%02d-%02d %02d:%02d:%02d\r\n", cur_tm->tm_year + 1900, cur_tm->tm_mon + 1,
                cur_tm->tm_mday, cur_tm->tm_hour, cur_tm->tm_min, cur_tm->tm_sec);
     }
 }
diff --git a/src/syscalls.c b/src/syscalls.c
index 0ef78de..eb7a265 100644
--- a/src/syscalls.c
+++ b/src/syscalls.c
@@ -1,5 +1,8 @@
 #include <sys/time.h>
+#include <sys/errno.h>
 
+#include "FreeRTOS.h"
+#include "task.h"
 #include "MK60D10.h"
 
 
@@ -9,3 +12,31 @@ int _gettimeofday(struct timeval *restrict tp, void *restrict tzp) {
 
     return 0;
 }
+
+caddr_t _sbrk(int incr)
+{
+    extern char end __asm("end");
+    extern char heap_limit __asm("__HeapLimit");
+    static char *heap_end;
+    char *prev_heap_end;
+
+    taskENTER_CRITICAL();
+
+    if (heap_end == NULL)
+        heap_end = &end;
+
+    prev_heap_end = heap_end;
+
+    if (heap_end + incr > &heap_limit)
+    {
+        errno = ENOMEM;
+        taskEXIT_CRITICAL();
+        return (caddr_t)-1;
+    }
+
+    heap_end += incr;
+
+    taskEXIT_CRITICAL();
+
+    return (caddr_t)prev_heap_end;
+}
\ No newline at end of file
diff --git a/src/system_utilities.c b/src/system_utilities.c
index 0e7528c..cf14b54 100644
--- a/src/system_utilities.c
+++ b/src/system_utilities.c
@@ -1,10 +1,10 @@
+#include <stdio.h>
+
 #include "board.h"
 #include "clock_config.h"
 #include "peripherals.h"
 #include "pin_mux.h"
 
-#include "fsl_debug_console.h"
-
 #define SRAM_BASE (0x60000000)
 #define SRAM_SIZE (512 * 1024)
 
@@ -95,25 +95,25 @@ void print_hardware(void) {
         break;
     }
 
-    PRINTF("This is %s with Rev. (Mask Set): %s, %s pins.\r\n", family_str, rev_str, pin_str);
+    printf("This is %s with Rev. (Mask Set): %s, %s pins.\r\n", family_str, rev_str, pin_str);
 }
 
 void sram_test(void) {
-    PRINTF("SRAM write... ");
+    printf("SRAM write... ");
     for(uint32_t i = SRAM_BASE; i < SRAM_BASE + SRAM_SIZE; i += 4) {
         *(volatile uint32_t *)i = i;
     }
 
-    PRINTF("done, SRAM read... ");
+    printf("done, SRAM read... ");
 
     for(uint32_t i = SRAM_BASE; i < SRAM_BASE + SRAM_SIZE; i += 4) {
         if(*(volatile uint32_t *)i != i) {
-            PRINTF("error.\r\n");
+            printf("error.\r\n");
             return;
         }
     }
 
-    PRINTF("done.\r\n");
+    printf("done.\r\n");
 }
 
 int set_rtc_time(int sec) {