diff --git a/client/emv/emv_roca.c b/client/emv/emv_roca.c
index 391a101b..3701ddf8 100644
--- a/client/emv/emv_roca.c
+++ b/client/emv/emv_roca.c
@@ -23,6 +23,7 @@
 
 #include "emv_roca.h"
 
+#include <stddef.h>
 #include <stdint.h>
 #include <stdbool.h>
 
@@ -91,7 +92,7 @@ void print_mpi(const char *msg, int radix, const mbedtls_mpi *X) {
 	size_t len = 0;
 	
 	mbedtls_mpi_write_string(X, radix, Xchar, sizeof(Xchar), &len);	
-	printf("%s[%d] %s\n", msg, len, Xchar);	
+	printf("%s[%zd] %s\n", msg, len, Xchar);	
 }
 
 bool emv_rocacheck(const unsigned char *buf, size_t buflen, bool verbose) {
diff --git a/client/emv/emv_roca.h b/client/emv/emv_roca.h
index ec3e9e43..b0b9a0ea 100644
--- a/client/emv/emv_roca.h
+++ b/client/emv/emv_roca.h
@@ -24,7 +24,7 @@
 #ifndef EMV_ROCA_H__
 #define EMV_ROCA_H__
 
-#include <stdint.h>
+#include <stddef.h>
 #include <stdbool.h>
 
 #define ROCA_PRINTS_LENGTH	17