diff --git a/tools/regression/netinet/udpzerobyte/udpzerobyte.c b/tools/regression/netinet/udpzerobyte/udpzerobyte.c
index c396fc8cce80..c19149233deb 100644
--- a/tools/regression/netinet/udpzerobyte/udpzerobyte.c
+++ b/tools/regression/netinet/udpzerobyte/udpzerobyte.c
@@ -80,7 +80,7 @@ test(int domain, const char *domainstr, struct sockaddr *sa, socklen_t salen)
 
 	size = recv(sock_receive, NULL, 0, 0);
 	if (size > 0)
-		errx(-1, "Protocol %s recv(sock_receive, NULL, 0) before: %d",
+		errx(-1, "Protocol %s recv(sock_receive, NULL, 0) before: %zd",
 		    domainstr, size);
 	else if (size < 0)
 		err(-1, "Protocol %s recv(sock_receive, NULL, 0) before",
@@ -98,7 +98,7 @@ test(int domain, const char *domainstr, struct sockaddr *sa, socklen_t salen)
 
 	size = recv(sock_receive, NULL, 0, 0);
 	if (size > 0)
-		errx(-1, "Protocol %s recv(sock_receive, NULL, 0) after: %d",
+		errx(-1, "Protocol %s recv(sock_receive, NULL, 0) after: %zd",
 		    domainstr, size);
 	else if (size < 0)
 		err(-1, "Protocol %s recv(sock_receive, NULL, 0) after",
diff --git a/tools/regression/netipx/ipxdgramloopback/ipxdgramloopback.c b/tools/regression/netipx/ipxdgramloopback/ipxdgramloopback.c
index b969b48b433c..73b6a2a99a9b 100644
--- a/tools/regression/netipx/ipxdgramloopback/ipxdgramloopback.c
+++ b/tools/regression/netipx/ipxdgramloopback/ipxdgramloopback.c
@@ -95,7 +95,7 @@ main(int argc, char *argv[])
 	if (len < 0)
 		err(-1, "sendto()");
 	if (len != sizeof(packet))
-		errx(-1, "sendto(): short send (%d length, %d sent)",
+		errx(-1, "sendto(): short send (%zu length, %zd sent)",
 		    sizeof(packet), len);
 
 	sleep(1);	/* Arbitrary non-zero amount. */
@@ -105,7 +105,7 @@ main(int argc, char *argv[])
 	if (len < 0)
 		err(-1, "recv()");
 	if (len != sizeof(packet))
-		errx(-1, "recv(): short receive (%d length, %d received)",
+		errx(-1, "recv(): short receive (%zu length, %zd received)",
 		    sizeof(packet), len);
 
 	for (i = 0; i < PACKETLEN; i++) {
diff --git a/tools/regression/ufs/uprintf/ufs_uprintf.c b/tools/regression/ufs/uprintf/ufs_uprintf.c
index d9f7125a8c47..17aa71ec0668 100644
--- a/tools/regression/ufs/uprintf/ufs_uprintf.c
+++ b/tools/regression/ufs/uprintf/ufs_uprintf.c
@@ -86,7 +86,7 @@ fill_blocks(void)
 		if (len < 0)
 			break;
 		if (len != BLOCKSIZE) {
-			warnx("fill_blocks: write(%d) returned %d",
+			warnx("fill_blocks: write(%d) returned %zd",
 			    BLOCKSIZE, len);
 			close(fd);
 			(void)unlink(BLOCKS_FILENAME);