diff --git a/tests/zfs-tests/cmd/largest_file/largest_file.c b/tests/zfs-tests/cmd/largest_file/largest_file.c
index 1cf7529f13ec..286232da5b19 100644
--- a/tests/zfs-tests/cmd/largest_file/largest_file.c
+++ b/tests/zfs-tests/cmd/largest_file/largest_file.c
@@ -64,7 +64,7 @@ main(int argc, char **argv)
 	offset_t	llseek_ret = 0;
 	int		write_ret = 0;
 	int		err = 0;
-	char		mybuf[5];
+	char		mybuf[5] = "aaaa\0";
 	char		*testfile;
 	mode_t		mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
 
@@ -78,30 +78,31 @@ main(int argc, char **argv)
 
 	fd = open(testfile, O_CREAT | O_RDWR, mode);
 	if (fd < 0) {
-		perror("Failed to create testfile");
 		err = errno;
-		goto out;
+		perror("Failed to create testfile");
+		free(testfile);
+		return (err);
 	}
 
 	llseek_ret = lseek64(fd, offset, SEEK_SET);
 	if (llseek_ret < 0) {
-		perror("Failed to seek to end of testfile");
 		err = errno;
+		perror("Failed to seek to end of testfile");
 		goto out;
 	}
 
 	write_ret = write(fd, mybuf, 1);
 	if (write_ret < 0) {
-		perror("Failed to write to end of file");
 		err = errno;
+		perror("Failed to write to end of file");
 		goto out;
 	}
 
 	offset = 0;
 	llseek_ret = lseek64(fd, offset, SEEK_CUR);
 	if (llseek_ret < 0) {
-		perror("Failed to seek to end of file");
 		err = errno;
+		perror("Failed to seek to end of file");
 		goto out;
 	}
 
@@ -111,8 +112,8 @@ main(int argc, char **argv)
 			(void) printf("write errno=EFBIG: success\n");
 			err = 0;
 		} else {
-			perror("Did not receive EFBIG");
 			err = errno;
+			perror("Did not receive EFBIG");
 		}
 	} else {
 		(void) printf("write completed successfully, test failed\n");
@@ -122,6 +123,7 @@ main(int argc, char **argv)
 out:
 	(void) unlink(testfile);
 	free(testfile);
+	close(fd);
 	return (err);
 }
 
diff --git a/tests/zfs-tests/cmd/mmapwrite/mmapwrite.c b/tests/zfs-tests/cmd/mmapwrite/mmapwrite.c
index 2eca124696e0..190d31af3aaa 100644
--- a/tests/zfs-tests/cmd/mmapwrite/mmapwrite.c
+++ b/tests/zfs-tests/cmd/mmapwrite/mmapwrite.c
@@ -28,6 +28,7 @@
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <sys/mman.h>
 #include <pthread.h>
 
@@ -67,9 +68,11 @@ int
 main(int argc, char **argv)
 {
 	int fd;
-	char buf[BUFSIZ];
+	char buf[1024];
 	pthread_t tid;
 
+	memset(buf, 'a', sizeof (buf));
+
 	if (argc != 2) {
 		(void) printf("usage: %s <file name>\n", argv[0]);
 		exit(1);
@@ -83,15 +86,19 @@ main(int argc, char **argv)
 	(void) pthread_setconcurrency(2);
 	if (pthread_create(&tid, NULL, mapper, &fd) != 0) {
 		perror("pthread_create");
+		close(fd);
 		exit(1);
 	}
 	for (;;) {
 		if (write(fd, buf, sizeof (buf)) == -1) {
 			perror("write");
+			close(fd);
 			exit(1);
 		}
 	}
 
+	close(fd);
+
 	/* NOTREACHED */
 	return (0);
 }
diff --git a/tests/zfs-tests/cmd/randfree_file/randfree_file.c b/tests/zfs-tests/cmd/randfree_file/randfree_file.c
index 05797448c90a..c708d647e8b9 100644
--- a/tests/zfs-tests/cmd/randfree_file/randfree_file.c
+++ b/tests/zfs-tests/cmd/randfree_file/randfree_file.c
@@ -32,6 +32,7 @@
 #include <sys/types.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <string.h>
 #include <linux/falloc.h>
 
 /*
@@ -54,7 +55,7 @@ int
 main(int argc, char *argv[])
 {
 	char *filename = NULL;
-	char *buf;
+	char *buf = NULL;
 	size_t filesize = 0;
 	off_t start_off = 0;
 	off_t off_len = 0;
@@ -88,11 +89,18 @@ main(int argc, char *argv[])
 		return (1);
 	}
 
-	buf = (char *)malloc(filesize);
+	buf = (char *)calloc(1, filesize);
+	if (buf == NULL) {
+		perror("write");
+		close(fd);
+		return (1);
+	}
+	memset(buf, 'c', filesize);
 
 	if (write(fd, buf, filesize) < filesize) {
 		free(buf);
 		perror("write");
+		close(fd);
 		return (1);
 	}
 
@@ -102,14 +110,16 @@ main(int argc, char *argv[])
 	if (fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 	    start_off, off_len) < 0) {
 		perror("fallocate");
+		close(fd);
 		return (1);
 	}
 #else /* !(defined(FALLOC_FL_PUNCH_HOLE) && defined(FALLOC_FL_KEEP_SIZE)) */
 	{
 		perror("FALLOC_FL_PUNCH_HOLE unsupported");
+		close(fd);
 		return (1);
 	}
 #endif /* defined(FALLOC_FL_PUNCH_HOLE) && defined(FALLOC_FL_KEEP_SIZE) */
-
+	close(fd);
 	return (0);
 }