diff --git a/armsrc/iso14443a.c b/armsrc/iso14443a.c
index cd64bae36..8f419aebc 100644
--- a/armsrc/iso14443a.c
+++ b/armsrc/iso14443a.c
@@ -682,12 +682,12 @@ void RAMFUNC SniffIso14443a(uint8_t param) {
     uint32_t rx_samples = 0;
 
     // loop and listen
-    while (!BUTTON_PRESS()) {
+    while (BUTTON_PRESS() == false) {
         WDT_HIT();
         LED_A_ON();
 
-        int register readBufDataP = data - dma->buf;
-        int register dmaBufDataP = DMA_BUFFER_SIZE - AT91C_BASE_PDC_SSC->PDC_RCR;
+        register int readBufDataP = data - dma->buf;
+        register int dmaBufDataP = DMA_BUFFER_SIZE - AT91C_BASE_PDC_SSC->PDC_RCR;
         if (readBufDataP <= dmaBufDataP)
             dataLen = dmaBufDataP - readBufDataP;
         else