diff --git a/armsrc/iso14443b.c b/armsrc/iso14443b.c
index c3c61e980..09c5e775e 100644
--- a/armsrc/iso14443b.c
+++ b/armsrc/iso14443b.c
@@ -41,7 +41,7 @@
 
 // defaults to 2000ms
 #ifndef FWT_TIMEOUT_14B
-# define FWT_TIMEOUT_14B  35312
+# define FWT_TIMEOUT_14B  35312U
 #endif
 
 // 1 tick == 1/13.56 mhz
@@ -178,7 +178,7 @@ static void CodeIso14443bAsTag(const uint8_t *cmd, int len) {
 
     // Send TR1.
     // 10-11 ETU * 4times samples ONES
-    for (i = 0; i < 20; i++) {
+    for (i = 0; i < 10; i++) {
         SEND4STUFFBIT(1);
     }
 
@@ -321,7 +321,7 @@ static void Demod14bInit(uint8_t *data, uint16_t max_len) {
 * @param timeout is in frame wait time, fwt, measured in ETUs
 */
 static void iso14b_set_timeout(uint32_t timeout) {
-#define MAX_TIMEOUT 40542464  // 13560000Hz * 1000ms / (2^32-1) * (8*16)
+#define MAX_TIMEOUT 40542464U  // 13560000Hz * 1000ms / (2^32-1) * (8*16)
     if (timeout > MAX_TIMEOUT)
         timeout = MAX_TIMEOUT;