diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
index 1a458f604..459445bb7 100644
--- a/cmd/zdb/zdb.c
+++ b/cmd/zdb/zdb.c
@@ -2888,7 +2888,7 @@ find_zpool(char **target, nvlist_t **configp, int dirc, char **dirv)
 	nvlist_t *match = NULL;
 	char *name = NULL;
 	char *sepp = NULL;
-	char sep;
+	char sep = 0;
 	int count = 0;
 	importargs_t args = { 0 };
 
diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index 22426ebfd..9cb69c1bf 100644
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -671,7 +671,7 @@ zfs_do_create(int argc, char **argv)
 {
 	zfs_type_t type = ZFS_TYPE_FILESYSTEM;
 	zfs_handle_t *zhp = NULL;
-	uint64_t volsize;
+	uint64_t volsize = 0;
 	int c;
 	boolean_t noreserve = B_FALSE;
 	boolean_t bflag = B_FALSE;
@@ -4060,7 +4060,7 @@ int
 main(int argc, char **argv)
 {
 	int ret;
-	int i;
+	int i = 0;
 	char *progname;
 	char *cmdname;
 
@@ -4139,6 +4139,7 @@ main(int argc, char **argv)
 			(void) fprintf(stderr, gettext("unrecognized "
 			    "command '%s'\n"), cmdname);
 			usage(B_FALSE);
+			ret = 1;
 		}
 		libzfs_mnttab_cache(g_zfs, B_FALSE);
 	}
diff --git a/cmd/zpool/zpool_main.c b/cmd/zpool/zpool_main.c
index 85a51de40..fa16836fe 100644
--- a/cmd/zpool/zpool_main.c
+++ b/cmd/zpool/zpool_main.c
@@ -3269,7 +3269,7 @@ print_scan_status(pool_scan_stat_t *ps)
 	 */
 	if (ps->pss_state == DSS_FINISHED) {
 		uint64_t minutes_taken = (end - start) / 60;
-		char *fmt;
+		char *fmt = NULL;
 
 		if (ps->pss_func == POOL_SCAN_SCRUB) {
 			fmt = gettext("scrub repaired %s in %lluh%um with "
@@ -4392,7 +4392,7 @@ int
 main(int argc, char **argv)
 {
 	int ret;
-	int i;
+	int i = 0;
 	char *cmdname;
 
 	(void) setlocale(LC_ALL, "");
@@ -4450,6 +4450,7 @@ main(int argc, char **argv)
 		(void) fprintf(stderr, gettext("unrecognized "
 		    "command '%s'\n"), cmdname);
 		usage(B_FALSE);
+		ret = 1;
 	}
 
 	libzfs_fini(g_zfs);
diff --git a/cmd/zpool/zpool_vdev.c b/cmd/zpool/zpool_vdev.c
index 53c2e60b7..0c224903d 100644
--- a/cmd/zpool/zpool_vdev.c
+++ b/cmd/zpool/zpool_vdev.c
@@ -548,7 +548,7 @@ get_replication(nvlist_t *nvroot, boolean_t fatal)
 	uint_t c, children;
 	nvlist_t *nv;
 	char *type;
-	replication_level_t lastrep, rep, *ret;
+	replication_level_t lastrep = { 0 }, rep, *ret;
 	boolean_t dontreport;
 
 	ret = safe_malloc(sizeof (replication_level_t));
diff --git a/lib/libzfs/libzfs_dataset.c b/lib/libzfs/libzfs_dataset.c
index 32cdd636a..a0146b4e4 100644
--- a/lib/libzfs/libzfs_dataset.c
+++ b/lib/libzfs/libzfs_dataset.c
@@ -1362,7 +1362,7 @@ zfs_prop_set(zfs_handle_t *zhp, const char *propname, const char *propval)
 	zfs_prop_t prop;
 	boolean_t do_prefix;
 	uint64_t idx;
-	int added_resv;
+	int added_resv = 0;
 
 	(void) snprintf(errbuf, sizeof (errbuf),
 	    dgettext(TEXT_DOMAIN, "cannot set property for '%s'"),
@@ -2791,7 +2791,7 @@ zfs_create_ancestors(libzfs_handle_t *hdl, const char *path)
 {
 	int prefix;
 	char *path_copy;
-	int rc;
+	int rc = 0;
 
 	if (check_parents(hdl, path, NULL, B_TRUE, &prefix) != 0)
 		return (-1);
@@ -3348,8 +3348,8 @@ zfs_rollback(zfs_handle_t *zhp, zfs_handle_t *snap, boolean_t force)
 	int err;
 	zfs_cmd_t zc = { "\0", "\0", "\0", "\0", 0 };
 	boolean_t restore_resv = 0;
-	uint64_t old_volsize, new_volsize;
-	zfs_prop_t resv_prop;
+	uint64_t old_volsize = 0, new_volsize;
+	zfs_prop_t resv_prop = { 0 };
 
 	assert(zhp->zfs_type == ZFS_TYPE_FILESYSTEM ||
 	    zhp->zfs_type == ZFS_TYPE_VOLUME);
@@ -3579,6 +3579,7 @@ zfs_rename(zfs_handle_t *zhp, const char *target, boolean_t recursive)
 			    "child dataset with inherited mountpoint is used "
 			    "in a non-global zone"));
 			(void) zfs_error(hdl, EZFS_ZONED, errbuf);
+			ret = -1;
 			goto error;
 		}
 
diff --git a/lib/libzfs/libzfs_import.c b/lib/libzfs/libzfs_import.c
index 9629ab083..386ab002f 100644
--- a/lib/libzfs/libzfs_import.c
+++ b/lib/libzfs/libzfs_import.c
@@ -434,7 +434,7 @@ get_configs(libzfs_handle_t *hdl, pool_list_t *pl, boolean_t active_ok)
 	pool_entry_t *pe;
 	vdev_entry_t *ve;
 	config_entry_t *ce;
-	nvlist_t *ret = NULL, *config = NULL, *tmp, *nvtop, *nvroot;
+	nvlist_t *ret = NULL, *config = NULL, *tmp = NULL, *nvtop, *nvroot;
 	nvlist_t **spares, **l2cache;
 	uint_t i, nspares, nl2cache;
 	boolean_t config_seen;
diff --git a/lib/libzfs/libzfs_util.c b/lib/libzfs/libzfs_util.c
index fbed42f06..8277bdb02 100644
--- a/lib/libzfs/libzfs_util.c
+++ b/lib/libzfs/libzfs_util.c
@@ -956,7 +956,7 @@ zprop_print_one_property(const char *name, zprop_get_cbdata_t *cbp,
     const char *source, const char *recvd_value)
 {
 	int i;
-	const char *str;
+	const char *str = NULL;
 	char buf[128];
 
 	/*
diff --git a/module/nvpair/nvpair.c b/module/nvpair/nvpair.c
index c675684c8..282e0f8a6 100644
--- a/module/nvpair/nvpair.c
+++ b/module/nvpair/nvpair.c
@@ -1611,10 +1611,10 @@ nvlist_lookup_nvpair_ei_sep(nvlist_t *nvl, const char *name, const char sep,
 {
 	nvpair_t	*nvp;
 	const char	*np;
-	char		*sepp;
+	char		*sepp=NULL;
 	char		*idxp, *idxep;
 	nvlist_t	**nva;
-	long		idx;
+	long		idx = 0;
 	int		n;
 
 	if (ip)
diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 96c3fb702..1d7fd9e4c 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -2678,7 +2678,7 @@ arc_read_nolock(zio_t *pio, spa_t *spa, const blkptr_t *bp,
     uint32_t *arc_flags, const zbookmark_t *zb)
 {
 	arc_buf_hdr_t *hdr;
-	arc_buf_t *buf;
+	arc_buf_t *buf = NULL;
 	kmutex_t *hash_lock;
 	zio_t *rzio;
 	uint64_t guid = spa_guid(spa);
@@ -2760,7 +2760,7 @@ top:
 		uint64_t size = BP_GET_LSIZE(bp);
 		arc_callback_t	*acb;
 		vdev_t *vd = NULL;
-		uint64_t addr;
+		daddr_t addr = -1;
 		boolean_t devw = B_FALSE;
 
 		if (hdr == NULL) {
@@ -3038,7 +3038,7 @@ arc_release(arc_buf_t *buf, void *tag)
 	arc_buf_hdr_t *hdr;
 	kmutex_t *hash_lock = NULL;
 	l2arc_buf_hdr_t *l2hdr;
-	uint64_t buf_size;
+	uint64_t buf_size = 0;
 
 	/*
 	 * It would be nice to assert that if it's DMU metadata (level >
@@ -4062,7 +4062,7 @@ l2arc_read_done(zio_t *zio)
 static list_t *
 l2arc_list_locked(int list_num, kmutex_t **lock)
 {
-	list_t *list;
+	list_t *list = NULL;
 
 	ASSERT(list_num >= 0 && list_num <= 3);
 
@@ -4235,7 +4235,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
 	list_t *list;
 	uint64_t passed_sz, write_sz, buf_sz, headroom;
 	void *buf_data;
-	kmutex_t *hash_lock, *list_lock;
+	kmutex_t *hash_lock, *list_lock = NULL;
 	boolean_t have_lock, full;
 	l2arc_write_callback_t *cb;
 	zio_t *pio, *wzio;
diff --git a/module/zfs/dmu.c b/module/zfs/dmu.c
index f2b3f2ba7..732742f33 100644
--- a/module/zfs/dmu.c
+++ b/module/zfs/dmu.c
@@ -355,7 +355,7 @@ dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset, uint64_t length,
 	uint32_t dbuf_flags;
 	int err;
 	zio_t *zio;
-	hrtime_t start;
+	hrtime_t start = 0;
 
 	ASSERT(length <= DMU_MAX_ACCESS);
 
diff --git a/module/zfs/dmu_objset.c b/module/zfs/dmu_objset.c
index b3a830217..2d06897db 100644
--- a/module/zfs/dmu_objset.c
+++ b/module/zfs/dmu_objset.c
@@ -1331,7 +1331,7 @@ dmu_objset_userquota_get_ids(dnode_t *dn, boolean_t before, dmu_tx_t *tx)
 	objset_t *os = dn->dn_objset;
 	void *data = NULL;
 	dmu_buf_impl_t *db = NULL;
-	uint64_t *user, *group;
+	uint64_t *user = NULL, *group = NULL;
 	int flags = dn->dn_id_flags;
 	int error;
 	boolean_t have_spill = B_FALSE;
diff --git a/module/zfs/dsl_dataset.c b/module/zfs/dsl_dataset.c
index 34fd758c4..226e98828 100644
--- a/module/zfs/dsl_dataset.c
+++ b/module/zfs/dsl_dataset.c
@@ -387,7 +387,7 @@ dsl_dataset_get_ref(dsl_pool_t *dp, uint64_t dsobj, void *tag,
 
 	ds = dmu_buf_get_user(dbuf);
 	if (ds == NULL) {
-		dsl_dataset_t *winner;
+		dsl_dataset_t *winner = NULL;
 
 		ds = kmem_zalloc(sizeof (dsl_dataset_t), KM_SLEEP);
 		ds->ds_dbuf = dbuf;
diff --git a/module/zfs/lzjb.c b/module/zfs/lzjb.c
index ab3de51b7..ad9e423f8 100644
--- a/module/zfs/lzjb.c
+++ b/module/zfs/lzjb.c
@@ -50,7 +50,7 @@ lzjb_compress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
 {
 	uchar_t *src = s_start;
 	uchar_t *dst = d_start;
-	uchar_t *cpy, *copymap;
+	uchar_t *cpy, *copymap = NULL;
 	int copymask = 1 << (NBBY - 1);
 	int mlen, offset, hash;
 	uint16_t *hp;
@@ -99,7 +99,7 @@ lzjb_decompress(void *s_start, void *d_start, size_t s_len, size_t d_len, int n)
 	uchar_t *src = s_start;
 	uchar_t *dst = d_start;
 	uchar_t *d_end = (uchar_t *)d_start + d_len;
-	uchar_t *cpy, copymap;
+	uchar_t *cpy, copymap = 0;
 	int copymask = 1 << (NBBY - 1);
 
 	while (dst < d_end) {
diff --git a/module/zfs/refcount.c b/module/zfs/refcount.c
index a659c0742..a61554606 100644
--- a/module/zfs/refcount.c
+++ b/module/zfs/refcount.c
@@ -110,7 +110,7 @@ refcount_count(refcount_t *rc)
 int64_t
 refcount_add_many(refcount_t *rc, uint64_t number, void *holder)
 {
-	reference_t *ref;
+	reference_t *ref = NULL;
 	int64_t count;
 
 	if (reference_tracking_enable) {
diff --git a/module/zfs/sa.c b/module/zfs/sa.c
index 4e71c407f..37b815f94 100644
--- a/module/zfs/sa.c
+++ b/module/zfs/sa.c
@@ -642,7 +642,7 @@ sa_build_layouts(sa_handle_t *hdl, sa_bulk_attr_t *attr_desc, int attr_count,
 	int buf_space;
 	sa_attr_type_t *attrs, *attrs_start;
 	int i, lot_count;
-	int hdrsize, spillhdrsize;
+	int hdrsize, spillhdrsize = 0;
 	int used;
 	dmu_object_type_t bonustype;
 	sa_lot_t *lot;
@@ -813,7 +813,7 @@ sa_attr_table_setup(objset_t *os, sa_attr_reg_t *reg_attrs, int count)
 {
 	sa_os_t *sa = os->os_sa;
 	uint64_t sa_attr_count = 0;
-	uint64_t sa_reg_count;
+	uint64_t sa_reg_count = 0;
 	int error = 0;
 	uint64_t attr_value;
 	sa_attr_table_t *tb;
@@ -1619,7 +1619,7 @@ sa_modify_attrs(sa_handle_t *hdl, sa_attr_type_t newattr,
 	sa_bulk_attr_t *attr_desc;
 	void *old_data[2];
 	int bonus_attr_count = 0;
-	int bonus_data_size, spill_data_size;
+	int bonus_data_size = 0, spill_data_size = 0;
 	int spill_attr_count = 0;
 	int error;
 	uint16_t length;
diff --git a/module/zfs/spa.c b/module/zfs/spa.c
index 0711102b4..d11f93dbe 100644
--- a/module/zfs/spa.c
+++ b/module/zfs/spa.c
@@ -334,7 +334,7 @@ spa_prop_validate(spa_t *spa, nvlist_t *props)
 {
 	nvpair_t *elem;
 	int error = 0, reset_bootfs = 0;
-	uint64_t objnum;
+	uint64_t objnum = 0;
 
 	elem = NULL;
 	while ((elem = nvlist_next_nvpair(props, elem)) != NULL) {
@@ -1144,7 +1144,7 @@ spa_load_l2cache(spa_t *spa)
 	uint_t nl2cache;
 	int i, j, oldnvdevs;
 	uint64_t guid;
-	vdev_t *vd, **oldvdevs, **newvdevs;
+	vdev_t *vd, **oldvdevs, **newvdevs = NULL;
 	spa_aux_vdev_t *sav = &spa->spa_l2cache;
 
 	ASSERT(spa_config_held(spa, SCL_ALL, RW_WRITER) == SCL_ALL);
@@ -4019,7 +4019,7 @@ spa_vdev_detach(spa_t *spa, uint64_t guid, uint64_t pguid, int replace_done)
 	ASSERTV(vdev_t *rvd = spa->spa_root_vdev;)
 	vdev_t *vd, *pvd, *cvd, *tvd;
 	boolean_t unspare = B_FALSE;
-	uint64_t unspare_guid;
+	uint64_t unspare_guid = 0;
 	char *vdpath;
 	int c, t;
 
diff --git a/module/zfs/spa_misc.c b/module/zfs/spa_misc.c
index cd8a6c875..32ef51db1 100644
--- a/module/zfs/spa_misc.c
+++ b/module/zfs/spa_misc.c
@@ -399,7 +399,7 @@ spa_lookup(const char *name)
 	static spa_t search;	/* spa_t is large; don't allocate on stack */
 	spa_t *spa;
 	avl_index_t where;
-	char c;
+	char c = 0;
 	char *cp;
 
 	ASSERT(MUTEX_HELD(&spa_namespace_lock));
diff --git a/module/zfs/vdev_file.c b/module/zfs/vdev_file.c
index 8c22aa531..f31389a6d 100644
--- a/module/zfs/vdev_file.c
+++ b/module/zfs/vdev_file.c
@@ -143,7 +143,7 @@ vdev_file_io_start(zio_t *zio)
 {
 	vdev_t *vd = zio->io_vd;
 	vdev_file_t *vf = vd->vdev_tsd;
-	ssize_t resid;
+	ssize_t resid = 0;
 
 	if (zio->io_type == ZIO_TYPE_IOCTL) {
 		/* XXPOLICY */
diff --git a/module/zfs/vdev_label.c b/module/zfs/vdev_label.c
index 8b400879b..3774d7152 100644
--- a/module/zfs/vdev_label.c
+++ b/module/zfs/vdev_label.c
@@ -612,7 +612,7 @@ vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
 	char *buf;
 	size_t buflen;
 	int error;
-	uint64_t spare_guid, l2cache_guid;
+	uint64_t spare_guid = 0, l2cache_guid = 0;
 	int flags = ZIO_FLAG_CONFIG_WRITER | ZIO_FLAG_CANFAIL;
 	int c, l;
 	vdev_t *pvd;
diff --git a/module/zfs/vdev_raidz.c b/module/zfs/vdev_raidz.c
index af2de40ac..ef2054233 100644
--- a/module/zfs/vdev_raidz.c
+++ b/module/zfs/vdev_raidz.c
@@ -1189,7 +1189,7 @@ vdev_raidz_matrix_reconstruct(raidz_map_t *rm, int n, int nmissing,
 	uint64_t ccount;
 	uint8_t *dst[VDEV_RAIDZ_MAXPARITY];
 	uint64_t dcount[VDEV_RAIDZ_MAXPARITY];
-	uint8_t log, val;
+	uint8_t log = 0, val;
 	int ll;
 	uint8_t *invlog[VDEV_RAIDZ_MAXPARITY];
 	uint8_t *p, *pp;
@@ -1638,8 +1638,11 @@ raidz_checksum_verify(zio_t *zio)
 {
 	zio_bad_cksum_t zbc;
 	raidz_map_t *rm = zio->io_vsd;
+	int ret;
 
-	int ret = zio_checksum_error(zio, &zbc);
+	bzero(&zbc, sizeof (zio_bad_cksum_t));
+
+	ret = zio_checksum_error(zio, &zbc);
 	if (ret != 0 && zbc.zbc_injected != 0)
 		rm->rm_ecksuminjected = 1;
 
@@ -1862,7 +1865,7 @@ vdev_raidz_io_done(zio_t *zio)
 	vdev_t *vd = zio->io_vd;
 	vdev_t *cvd;
 	raidz_map_t *rm = zio->io_vsd;
-	raidz_col_t *rc;
+	raidz_col_t *rc = NULL;
 	int unexpected_errors = 0;
 	int parity_errors = 0;
 	int parity_untried = 0;
diff --git a/module/zfs/zap_leaf.c b/module/zfs/zap_leaf.c
index 19a795db8..b867ac407 100644
--- a/module/zfs/zap_leaf.c
+++ b/module/zfs/zap_leaf.c
@@ -220,7 +220,7 @@ zap_leaf_array_create(zap_leaf_t *l, const char *buf,
 	uint16_t chunk_head;
 	uint16_t *chunkp = &chunk_head;
 	int byten = 0;
-	uint64_t value;
+	uint64_t value = 0;
 	int shift = (integer_size-1)*8;
 	int len = num_integers;
 
diff --git a/module/zfs/zfs_byteswap.c b/module/zfs/zfs_byteswap.c
index acf632bdb..6048eb124 100644
--- a/module/zfs/zfs_byteswap.c
+++ b/module/zfs/zfs_byteswap.c
@@ -51,7 +51,7 @@ zfs_ace_byteswap(void *buf, size_t size, boolean_t zfs_layout)
 {
 	caddr_t end;
 	caddr_t ptr;
-	zfs_ace_t *zacep;
+	zfs_ace_t *zacep = NULL;
 	ace_t *acep;
 	uint16_t entry_type;
 	size_t entry_size;
diff --git a/module/zfs/zfs_rlock.c b/module/zfs/zfs_rlock.c
index 7fd8f6020..4e3c176a3 100644
--- a/module/zfs/zfs_rlock.c
+++ b/module/zfs/zfs_rlock.c
@@ -460,7 +460,7 @@ static void
 zfs_range_unlock_reader(znode_t *zp, rl_t *remove)
 {
 	avl_tree_t *tree = &zp->z_range_avl;
-	rl_t *rl, *next;
+	rl_t *rl, *next = NULL;
 	uint64_t len;
 
 	/*
diff --git a/module/zfs/zil.c b/module/zfs/zil.c
index 751806d33..3c18d43fa 100644
--- a/module/zfs/zil.c
+++ b/module/zfs/zil.c
@@ -296,6 +296,8 @@ zil_parse(zilog_t *zilog, zil_parse_blk_func_t *parse_blk_func,
 	char *lrbuf, *lrp;
 	int error = 0;
 
+	bzero(&next_blk, sizeof(blkptr_t));
+
 	/*
 	 * Old logs didn't record the maximum zh_claim_lr_seq.
 	 */
@@ -317,7 +319,7 @@ zil_parse(zilog_t *zilog, zil_parse_blk_func_t *parse_blk_func,
 	for (blk = zh->zh_log; !BP_IS_HOLE(&blk); blk = next_blk) {
 		uint64_t blk_seq = blk.blk_cksum.zc_word[ZIL_ZC_SEQ];
 		int reclen;
-		char *end;
+		char *end = NULL;
 
 		if (blk_seq > claim_blk_seq)
 			break;