diff --git a/armsrc/appmain.c b/armsrc/appmain.c
index aa0f23d8f..5399b326a 100644
--- a/armsrc/appmain.c
+++ b/armsrc/appmain.c
@@ -1613,7 +1613,11 @@ static void PacketReceived(PacketCommandNG *packet) {
             break;
         }
         case CMD_SMART_SETCLOCK: {
-            SmartCardSetClock(packet->oldarg[0]);
+            struct p {
+                uint32_t new_clk;
+            } PACKED;
+            struct p *payload = (struct p *)packet->data.asBytes;
+            SmartCardSetClock(payload->new_clk);
             break;
         }
         case CMD_SMART_RAW: {
diff --git a/armsrc/i2c.c b/armsrc/i2c.c
index 1ca742893..7b858dd36 100644
--- a/armsrc/i2c.c
+++ b/armsrc/i2c.c
@@ -47,12 +47,6 @@ static void __attribute__((optimize("O0"))) I2CSpinDelayClk(uint16_t delay) {
 #define I2C_DELAY_2CLK    I2CSpinDelayClk(2)
 #define I2C_DELAY_XCLK(x) I2CSpinDelayClk((x))
 
-#define I2C_DELAY_100us   I2CSpinDelayClk( 100 / 3)
-#define I2C_DELAY_600us   I2CSpinDelayClk( 600 / 3)
-#define I2C_DELAY_10ms    I2CSpinDelayClk( 10 * 1000 / 3 )
-#define I2C_DELAY_30ms    I2CSpinDelayClk( 30 * 1000 / 3 )
-#define I2C_DELAY_100ms   I2CSpinDelayClk( 100 * 1000 / 3)
-
 #define  ISO7618_MAX_FRAME 255
 
 // try i2c bus recovery at 100kHz = 5us high, 5us low
@@ -134,11 +128,11 @@ void I2C_Reset_EnterMainProgram(void) {
     StartTicks();
     I2C_init();
     I2C_SetResetStatus(0, 0, 0);
-    I2C_DELAY_30ms;
+    WaitMS(30);
     I2C_SetResetStatus(1, 0, 0);
-    I2C_DELAY_30ms;
+    WaitMS(30);
     I2C_SetResetStatus(1, 1, 1);
-    I2C_DELAY_10ms;
+    WaitMS(10);
 }
 
 // Reset the SIM_Adapter, then enter the bootloader program
@@ -147,9 +141,9 @@ void I2C_Reset_EnterBootloader(void) {
     StartTicks();
     I2C_init();
     I2C_SetResetStatus(0, 1, 1);
-    I2C_DELAY_100ms;
+    WaitMS(100);
     I2C_SetResetStatus(1, 1, 1);
-    I2C_DELAY_10ms;
+    WaitMS(10);
 }
 
 // Wait for the clock to go High.
@@ -193,7 +187,7 @@ static bool WaitSCL_L_timeout(void) {
         if (!SCL_read)
             return true;
 
-        I2C_DELAY_100us;
+        WaitMS(1);
     }
     return (delay == 0);
 }
@@ -440,8 +434,7 @@ int16_t I2C_BufferRead(uint8_t *data, uint8_t len, uint8_t device_cmd, uint8_t d
 
     // extra wait  500us (514us measured)
     // 200us  (xx measured)
-//    WaitUS(600);
-    I2C_DELAY_600us;
+    WaitUS(600);
 
     bool bBreak = true;
     uint16_t readcount = 0;
@@ -811,8 +804,7 @@ void SmartCardUpgrade(uint64_t arg0) {
         }
 
         // writing takes time.
-//        WaitMS(50);
-        I2C_DELAY_100ms;
+        WaitMS(100);
 
         // read
         res = I2C_ReadFW(verfiydata, size, msb, lsb, I2C_DEVICE_ADDRESS_BOOT);
@@ -844,12 +836,10 @@ void SmartCardSetClock(uint64_t arg0) {
     LED_D_ON();
     set_tracing(true);
     I2C_Reset_EnterMainProgram();
-
     // Send SIM CLC
     // start [C0 05 xx] stop
     I2C_WriteByte(arg0, I2C_DEVICE_CMD_SIM_CLC, I2C_DEVICE_ADDRESS_MAIN);
-
-    reply_mix(CMD_ACK, 1, 0, 0, 0, 0);
+    reply_ng(CMD_SMART_SETCLOCK, PM3_SUCCESS, NULL, 0);
     set_tracing(false);
     LEDsoff();
 }
diff --git a/client/src/cmdsmartcard.c b/client/src/cmdsmartcard.c
index dc8205948..c6b2e66e1 100644
--- a/client/src/cmdsmartcard.c
+++ b/client/src/cmdsmartcard.c
@@ -791,14 +791,14 @@ static int CmdSmartReader(const char *Cmd) {
 static int CmdSmartSetClock(const char *Cmd) {
     uint8_t cmdp = 0;
     bool errors = false;
-    uint8_t clock1 = 0;
+    uint8_t new_clk = 0;
     while (param_getchar(Cmd, cmdp) != 0x00 && !errors) {
         switch (tolower(param_getchar(Cmd, cmdp))) {
             case 'h':
                 return usage_sm_setclock();
             case 'c':
-                clock1 = param_get8ex(Cmd, cmdp + 1, 2, 10);
-                if (clock1 > 2)
+                new_clk = param_get8ex(Cmd, cmdp + 1, 2, 10);
+                if (new_clk > 2)
                     errors = true;
 
                 cmdp += 2;
@@ -813,21 +813,26 @@ static int CmdSmartSetClock(const char *Cmd) {
     //Validations
     if (errors || cmdp == 0) return usage_sm_setclock();
 
+    struct {
+        uint32_t new_clk;
+    } PACKED payload;
+    
+    payload.new_clk = new_clk;
+
     clearCommandBuffer();
-    SendCommandMIX(CMD_SMART_SETCLOCK, clock1, 0, 0, NULL, 0);
+    SendCommandNG(CMD_SMART_SETCLOCK, (uint8_t*)&payload, sizeof(payload));
     PacketResponseNG resp;
-    if (!WaitForResponseTimeout(CMD_ACK, &resp, 2500)) {
+    if (!WaitForResponseTimeout(CMD_SMART_SETCLOCK, &resp, 2500)) {
         PrintAndLogEx(WARNING, "smart card select failed");
         return PM3_ETIMEOUT;
     }
 
-    uint8_t isok = resp.oldarg[0] & 0xFF;
-    if (!isok) {
+    if (resp.status != PM3_SUCCESS) {
         PrintAndLogEx(WARNING, "smart card set clock failed");
         return PM3_ESOFT;
     }
 
-    switch (clock1) {
+    switch (new_clk) {
         case 0:
             PrintAndLogEx(SUCCESS, "Clock changed to 16MHz giving 10800 baudrate");
             break;