diff --git a/.topdeps b/.topdeps
index 8b9694c75b..2cf45e3049 100644
--- a/.topdeps
+++ b/.topdeps
@@ -11,3 +11,4 @@ gcc-shadow
 gcc-64bit-constants
 gcc-ident-pragmas
 gcc-missing-braces
+gcc-fortify-source
diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index c8076b1780..fb9c4be6f0 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -1882,7 +1882,7 @@ zdb_dump_block_raw(void *buf, uint64_t size, int flags)
 {
 	if (flags & ZDB_FLAG_BSWAP)
 		byteswap_uint64_array(buf, size);
-	(void) write(2, buf, size);
+	VERIFY(write(fileno(stderr), buf, size) == size);
 }
 
 static void
diff --git a/cmd/ztest/ztest.c b/cmd/ztest/ztest.c
index fcfeef4dab..019c57385f 100644
--- a/cmd/ztest/ztest.c
+++ b/cmd/ztest/ztest.c
@@ -1171,7 +1171,7 @@ ztest_vdev_LUN_growth(ztest_args_t *za)
 		 */
 		if (fsize < 2 * zopt_vdev_size) {
 			size_t newsize = fsize + ztest_random(fsize / 32);
-			(void) ftruncate(fd, newsize);
+			VERIFY(ftruncate(fd, newsize) == 0);
 			if (zopt_verbose >= 6) {
 				(void) printf("%s grew from %lu to %lu bytes\n",
 				    dev_name, (ulong_t)fsize, (ulong_t)newsize);
diff --git a/lib/libzpool/kernel.c b/lib/libzpool/kernel.c
index 00e8ad09d2..a53ab265df 100644
--- a/lib/libzpool/kernel.c
+++ b/lib/libzpool/kernel.c
@@ -829,7 +829,7 @@ umem_out_of_memory(void)
 {
 	char errmsg[] = "out of memory -- generating core dump\n";
 
-	write(fileno(stderr), errmsg, sizeof (errmsg));
+	(void) fprintf(stderr, "%s", errmsg);
 	abort();
 	return (0);
 }