diff --git a/arch/arm/lib/semihosting.c b/arch/arm/lib/semihosting.c
index ed5e8e4..e32ad90 100644
--- a/arch/arm/lib/semihosting.c
+++ b/arch/arm/lib/semihosting.c
@@ -92,7 +92,7 @@
 		size_t len;
 	} read;
 
-	debug("%s: fd %ld, memp %p, len %lu\n", __func__, fd, memp, len);
+	debug("%s: fd %ld, memp %p, len %zu\n", __func__, fd, memp, len);
 
 	read.fd = fd;
 	read.memp = memp;
@@ -106,7 +106,7 @@
 		 * hard to maintain partial read loops and such, just fail
 		 * with an error message.
 		 */
-		printf("%s: ERROR ret %ld, fd %ld, len %lu memp %p\n",
+		printf("%s: ERROR ret %ld, fd %ld, len %zu memp %p\n",
 		       __func__, ret, fd, len, memp);
 		return -1;
 	}