diff --git a/lib/isc/ht.c b/lib/isc/ht.c
index d67f91b394..fa805c9a51 100644
--- a/lib/isc/ht.c
+++ b/lib/isc/ht.c
@@ -27,9 +27,22 @@ typedef struct isc_ht_node isc_ht_node_t;
 #define ISC_HT_MAGIC	 ISC_MAGIC('H', 'T', 'a', 'b')
 #define ISC_HT_VALID(ht) ISC_MAGIC_VALID(ht, ISC_HT_MAGIC)
 
+#define HT_NO_BITS    0
+#define HT_MIN_BITS   1
+#define HT_MAX_BITS   32
+#define HT_OVERCOMMIT 3
+
+#define HT_NEXTTABLE(idx)      ((idx == 0) ? 1 : 0)
+#define TRY_NEXTTABLE(idx, ht) (idx == ht->hindex && rehashing_in_progress(ht))
+
+#define GOLDEN_RATIO_32 0x61C88647
+
+#define HASHSIZE(bits) (UINT64_C(1) << (bits))
+
 struct isc_ht_node {
 	void *value;
 	isc_ht_node_t *next;
+	uint32_t hashval;
 	size_t keysize;
 	unsigned char key[];
 };
@@ -37,41 +50,203 @@ struct isc_ht_node {
 struct isc_ht {
 	unsigned int magic;
 	isc_mem_t *mctx;
-	size_t size;
-	size_t mask;
-	unsigned int count;
-	isc_ht_node_t **table;
+	size_t count;
+	size_t size[2];
+	uint8_t hashbits[2];
+	isc_ht_node_t **table[2];
+	uint8_t hindex;
+	uint32_t hiter; /* rehashing iterator */
 };
 
 struct isc_ht_iter {
 	isc_ht_t *ht;
 	size_t i;
+	uint8_t hindex;
 	isc_ht_node_t *cur;
 };
 
+static isc_ht_node_t *
+isc__ht_find(const isc_ht_t *ht, const unsigned char *key,
+	     const uint32_t keysize, const uint32_t hashval, const uint8_t idx);
+static void
+isc__ht_add(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
+	    const uint32_t hashval, const uint8_t idx, void *value);
+static isc_result_t
+isc__ht_delete(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
+	       const uint32_t hashval, const uint8_t idx);
+
+static uint32_t
+rehash_bits(isc_ht_t *ht, size_t newcount);
+
+static void
+hashtable_new(isc_ht_t *ht, const uint8_t idx, const uint8_t bits);
+static void
+hashtable_free(isc_ht_t *ht, const uint8_t idx);
+static void
+hashtable_rehash(isc_ht_t *ht, uint32_t newbits);
+static void
+hashtable_rehash_one(isc_ht_t *ht);
+static void
+maybe_rehash(isc_ht_t *ht, size_t newcount);
+
+static isc_result_t
+isc__ht_iter_next(isc_ht_iter_t *it);
+
+static bool
+isc__ht_node_match(isc_ht_node_t *node, const uint32_t hashval,
+		   const uint8_t *key, uint32_t keysize) {
+	return (node->hashval == hashval && node->keysize == keysize &&
+		memcmp(node->key, key, keysize) == 0);
+}
+
+static uint32_t
+hash_32(uint32_t val, unsigned int bits) {
+	REQUIRE(bits <= HT_MAX_BITS);
+	/* High bits are more random. */
+	return (val * GOLDEN_RATIO_32 >> (32 - bits));
+}
+
+static bool
+rehashing_in_progress(const isc_ht_t *ht) {
+	return (ht->table[HT_NEXTTABLE(ht->hindex)] != NULL);
+}
+
+static bool
+hashtable_is_overcommited(isc_ht_t *ht) {
+	return (ht->count >= (ht->size[ht->hindex] * HT_OVERCOMMIT));
+}
+
+static uint32_t
+rehash_bits(isc_ht_t *ht, size_t newcount) {
+	uint32_t newbits = ht->hashbits[ht->hindex];
+
+	while (newcount >= HASHSIZE(newbits) && newbits <= HT_MAX_BITS) {
+		newbits += 1;
+	}
+
+	return (newbits);
+}
+
+/*
+ * Rebuild the hashtable to reduce the load factor
+ */
+static void
+hashtable_rehash(isc_ht_t *ht, uint32_t newbits) {
+	uint8_t oldindex = ht->hindex;
+	uint32_t oldbits = ht->hashbits[oldindex];
+	uint8_t newindex = HT_NEXTTABLE(oldindex);
+
+	REQUIRE(ht->hashbits[oldindex] >= HT_MIN_BITS);
+	REQUIRE(ht->hashbits[oldindex] <= HT_MAX_BITS);
+	REQUIRE(ht->table[oldindex] != NULL);
+
+	REQUIRE(newbits <= HT_MAX_BITS);
+	REQUIRE(ht->hashbits[newindex] == HT_NO_BITS);
+	REQUIRE(ht->table[newindex] == NULL);
+
+	REQUIRE(newbits > oldbits);
+
+	hashtable_new(ht, newindex, newbits);
+
+	ht->hindex = newindex;
+
+	hashtable_rehash_one(ht);
+}
+
+static void
+hashtable_rehash_one(isc_ht_t *ht) {
+	isc_ht_node_t **newtable = ht->table[ht->hindex];
+	uint32_t oldsize = ht->size[HT_NEXTTABLE(ht->hindex)];
+	isc_ht_node_t **oldtable = ht->table[HT_NEXTTABLE(ht->hindex)];
+	isc_ht_node_t *node = NULL;
+	isc_ht_node_t *nextnode;
+
+	/* Find first non-empty node */
+	while (ht->hiter < oldsize && oldtable[ht->hiter] == NULL) {
+		ht->hiter++;
+	}
+
+	/* Rehashing complete */
+	if (ht->hiter == oldsize) {
+		hashtable_free(ht, HT_NEXTTABLE(ht->hindex));
+		ht->hiter = 0;
+		return;
+	}
+
+	/* Move the first non-empty node from old hashtable to new hashtable */
+	for (node = oldtable[ht->hiter]; node != NULL; node = nextnode) {
+		uint32_t hash = hash_32(node->hashval,
+					ht->hashbits[ht->hindex]);
+		nextnode = node->next;
+		node->next = newtable[hash];
+		newtable[hash] = node;
+	}
+
+	oldtable[ht->hiter] = NULL;
+
+	ht->hiter++;
+}
+
+static void
+maybe_rehash(isc_ht_t *ht, size_t newcount) {
+	uint32_t newbits = rehash_bits(ht, newcount);
+
+	if (ht->hashbits[ht->hindex] < newbits && newbits <= HT_MAX_BITS) {
+		hashtable_rehash(ht, newbits);
+	}
+}
+
+static void
+hashtable_new(isc_ht_t *ht, const uint8_t idx, const uint8_t bits) {
+	size_t size;
+	REQUIRE(ht->hashbits[idx] == HT_NO_BITS);
+	REQUIRE(ht->table[idx] == NULL);
+	REQUIRE(bits >= HT_MIN_BITS);
+	REQUIRE(bits <= HT_MAX_BITS);
+
+	ht->hashbits[idx] = bits;
+	ht->size[idx] = HASHSIZE(ht->hashbits[idx]);
+
+	size = ht->size[idx] * sizeof(isc_ht_node_t *);
+
+	ht->table[idx] = isc_mem_get(ht->mctx, size);
+	memset(ht->table[idx], 0, size);
+}
+
+static void
+hashtable_free(isc_ht_t *ht, const uint8_t idx) {
+	size_t size = ht->size[idx] * sizeof(isc_ht_node_t *);
+
+	for (size_t i = 0; i < ht->size[idx]; i++) {
+		isc_ht_node_t *node = ht->table[idx][i];
+		while (node != NULL) {
+			isc_ht_node_t *next = node->next;
+			ht->count--;
+			isc_mem_put(ht->mctx, node,
+				    sizeof(*node) + node->keysize);
+			node = next;
+		}
+	}
+
+	isc_mem_put(ht->mctx, ht->table[idx], size);
+	ht->hashbits[idx] = HT_NO_BITS;
+	ht->table[idx] = NULL;
+}
+
 void
 isc_ht_init(isc_ht_t **htp, isc_mem_t *mctx, uint8_t bits) {
 	isc_ht_t *ht = NULL;
-	size_t i;
 
 	REQUIRE(htp != NULL && *htp == NULL);
 	REQUIRE(mctx != NULL);
-	REQUIRE(bits >= 1 && bits <= (sizeof(size_t) * 8 - 1));
+	REQUIRE(bits >= 1 && bits <= HT_MAX_BITS);
 
-	ht = isc_mem_get(mctx, sizeof(struct isc_ht));
+	ht = isc_mem_get(mctx, sizeof(*ht));
+	*ht = (isc_ht_t){ 0 };
 
-	ht->mctx = NULL;
 	isc_mem_attach(mctx, &ht->mctx);
 
-	ht->size = ((size_t)1 << bits);
-	ht->mask = ((size_t)1 << bits) - 1;
-	ht->count = 0;
-
-	ht->table = isc_mem_get(ht->mctx, ht->size * sizeof(isc_ht_node_t *));
-
-	for (i = 0; i < ht->size; i++) {
-		ht->table[i] = NULL;
-	}
+	hashtable_new(ht, 0, bits);
 
 	ht->magic = ISC_HT_MAGIC;
 
@@ -81,123 +256,180 @@ isc_ht_init(isc_ht_t **htp, isc_mem_t *mctx, uint8_t bits) {
 void
 isc_ht_destroy(isc_ht_t **htp) {
 	isc_ht_t *ht;
-	size_t i;
 
 	REQUIRE(htp != NULL);
+	REQUIRE(ISC_HT_VALID(*htp));
 
 	ht = *htp;
 	*htp = NULL;
-
-	REQUIRE(ISC_HT_VALID(ht));
-
 	ht->magic = 0;
 
-	for (i = 0; i < ht->size; i++) {
-		isc_ht_node_t *node = ht->table[i];
-		while (node != NULL) {
-			isc_ht_node_t *next = node->next;
-			ht->count--;
-			isc_mem_put(ht->mctx, node,
-				    offsetof(isc_ht_node_t, key) +
-					    node->keysize);
-			node = next;
+	for (size_t i = 0; i <= 1; i++) {
+		if (ht->table[i] != NULL) {
+			hashtable_free(ht, i);
 		}
 	}
 
 	INSIST(ht->count == 0);
 
-	isc_mem_put(ht->mctx, ht->table, ht->size * sizeof(isc_ht_node_t *));
-	isc_mem_putanddetach(&ht->mctx, ht, sizeof(struct isc_ht));
+	isc_mem_putanddetach(&ht->mctx, ht, sizeof(*ht));
+}
+
+static void
+isc__ht_add(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
+	    const uint32_t hashval, const uint8_t idx, void *value) {
+	isc_ht_node_t *node;
+	uint32_t hash;
+
+	hash = hash_32(hashval, ht->hashbits[idx]);
+
+	node = isc_mem_get(ht->mctx, sizeof(*node) + keysize);
+	*node = (isc_ht_node_t){
+		.keysize = keysize,
+		.hashval = hashval,
+		.next = ht->table[idx][hash],
+		.value = value,
+	};
+
+	memmove(node->key, key, keysize);
+
+	ht->count++;
+	ht->table[idx][hash] = node;
 }
 
 isc_result_t
-isc_ht_add(isc_ht_t *ht, const unsigned char *key, uint32_t keysize,
+isc_ht_add(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
 	   void *value) {
-	isc_ht_node_t *node;
-	uint32_t hash;
+	uint32_t hashval;
 
 	REQUIRE(ISC_HT_VALID(ht));
 	REQUIRE(key != NULL && keysize > 0);
 
-	hash = isc_hash_function(key, keysize, true);
-	node = ht->table[hash & ht->mask];
-	while (node != NULL) {
-		if (keysize == node->keysize &&
-		    memcmp(key, node->key, keysize) == 0) {
-			return (ISC_R_EXISTS);
-		}
-		node = node->next;
+	if (rehashing_in_progress(ht)) {
+		/* Rehash in progress */
+		hashtable_rehash_one(ht);
+	} else if (hashtable_is_overcommited(ht)) {
+		/* Rehash requested */
+		maybe_rehash(ht, ht->count);
 	}
 
-	node = isc_mem_get(ht->mctx, offsetof(isc_ht_node_t, key) + keysize);
+	hashval = isc_hash32(key, keysize, true);
 
-	memmove(node->key, key, keysize);
-	node->keysize = keysize;
-	node->next = ht->table[hash & ht->mask];
-	node->value = value;
+	if (isc__ht_find(ht, key, keysize, hashval, ht->hindex) != NULL) {
+		return (ISC_R_EXISTS);
+	}
+
+	isc__ht_add(ht, key, keysize, hashval, ht->hindex, value);
 
-	ht->count++;
-	ht->table[hash & ht->mask] = node;
 	return (ISC_R_SUCCESS);
 }
 
-isc_result_t
-isc_ht_find(const isc_ht_t *ht, const unsigned char *key, uint32_t keysize,
-	    void **valuep) {
-	isc_ht_node_t *node;
+static isc_ht_node_t *
+isc__ht_find(const isc_ht_t *ht, const unsigned char *key,
+	     const uint32_t keysize, const uint32_t hashval,
+	     const uint8_t idx) {
 	uint32_t hash;
+	uint8_t findex = idx;
+
+nexttable:
+	hash = hash_32(hashval, ht->hashbits[findex]);
+	for (isc_ht_node_t *node = ht->table[findex][hash]; node != NULL;
+	     node = node->next)
+	{
+		if (isc__ht_node_match(node, hashval, key, keysize)) {
+			return (node);
+		}
+	}
+	if (TRY_NEXTTABLE(findex, ht)) {
+		/*
+		 * Rehashing in progress, check the other table
+		 */
+		findex = HT_NEXTTABLE(findex);
+		goto nexttable;
+	}
+
+	return (NULL);
+}
+
+isc_result_t
+isc_ht_find(const isc_ht_t *ht, const unsigned char *key,
+	    const uint32_t keysize, void **valuep) {
+	uint32_t hashval;
+	isc_ht_node_t *node;
 
 	REQUIRE(ISC_HT_VALID(ht));
 	REQUIRE(key != NULL && keysize > 0);
 	REQUIRE(valuep == NULL || *valuep == NULL);
 
-	hash = isc_hash_function(key, keysize, true);
-	node = ht->table[hash & ht->mask];
-	while (node != NULL) {
-		if (keysize == node->keysize &&
-		    memcmp(key, node->key, keysize) == 0) {
-			if (valuep != NULL) {
-				*valuep = node->value;
+	hashval = isc_hash32(key, keysize, true);
+
+	node = isc__ht_find(ht, key, keysize, hashval, ht->hindex);
+	if (node == NULL) {
+		return (ISC_R_NOTFOUND);
+	}
+
+	if (valuep != NULL) {
+		*valuep = node->value;
+	}
+	return (ISC_R_SUCCESS);
+}
+
+static isc_result_t
+isc__ht_delete(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
+	       const uint32_t hashval, const uint8_t idx) {
+	isc_ht_node_t *prev = NULL;
+	uint32_t hash;
+
+	hash = hash_32(hashval, ht->hashbits[idx]);
+
+	for (isc_ht_node_t *node = ht->table[idx][hash]; node != NULL;
+	     prev = node, node = node->next)
+	{
+		if (isc__ht_node_match(node, hashval, key, keysize)) {
+			if (prev == NULL) {
+				ht->table[idx][hash] = node->next;
+			} else {
+				prev->next = node->next;
 			}
+			isc_mem_put(ht->mctx, node,
+				    sizeof(*node) + node->keysize);
+			ht->count--;
+
 			return (ISC_R_SUCCESS);
 		}
-		node = node->next;
 	}
 
 	return (ISC_R_NOTFOUND);
 }
 
 isc_result_t
-isc_ht_delete(isc_ht_t *ht, const unsigned char *key, uint32_t keysize) {
-	isc_ht_node_t *node, *prev;
-	uint32_t hash;
+isc_ht_delete(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize) {
+	uint32_t hashval;
+	uint8_t hindex;
+	isc_result_t result;
 
 	REQUIRE(ISC_HT_VALID(ht));
 	REQUIRE(key != NULL && keysize > 0);
 
-	prev = NULL;
-	hash = isc_hash_function(key, keysize, true);
-	node = ht->table[hash & ht->mask];
-	while (node != NULL) {
-		if (keysize == node->keysize &&
-		    memcmp(key, node->key, keysize) == 0) {
-			if (prev == NULL) {
-				ht->table[hash & ht->mask] = node->next;
-			} else {
-				prev->next = node->next;
-			}
-			isc_mem_put(ht->mctx, node,
-				    offsetof(isc_ht_node_t, key) +
-					    node->keysize);
-			ht->count--;
-
-			return (ISC_R_SUCCESS);
-		}
-
-		prev = node;
-		node = node->next;
+	if (rehashing_in_progress(ht)) {
+		/* Rehash in progress */
+		hashtable_rehash_one(ht);
 	}
-	return (ISC_R_NOTFOUND);
+
+	hindex = ht->hindex;
+	hashval = isc_hash32(key, keysize, true);
+nexttable:
+	result = isc__ht_delete(ht, key, keysize, hashval, hindex);
+
+	if (result == ISC_R_NOTFOUND && TRY_NEXTTABLE(hindex, ht)) {
+		/*
+		 * Rehashing in progress, check the other table
+		 */
+		hindex = HT_NEXTTABLE(hindex);
+		goto nexttable;
+	}
+
+	return (result);
 }
 
 void
@@ -208,10 +440,10 @@ isc_ht_iter_create(isc_ht_t *ht, isc_ht_iter_t **itp) {
 	REQUIRE(itp != NULL && *itp == NULL);
 
 	it = isc_mem_get(ht->mctx, sizeof(isc_ht_iter_t));
-
-	it->ht = ht;
-	it->i = 0;
-	it->cur = NULL;
+	*it = (isc_ht_iter_t){
+		.ht = ht,
+		.hindex = ht->hindex,
+	};
 
 	*itp = it;
 }
@@ -226,25 +458,45 @@ isc_ht_iter_destroy(isc_ht_iter_t **itp) {
 	it = *itp;
 	*itp = NULL;
 	ht = it->ht;
-	isc_mem_put(ht->mctx, it, sizeof(isc_ht_iter_t));
+	isc_mem_put(ht->mctx, it, sizeof(*it));
 }
 
 isc_result_t
 isc_ht_iter_first(isc_ht_iter_t *it) {
+	isc_ht_t *ht;
+
 	REQUIRE(it != NULL);
 
+	ht = it->ht;
+
+	it->hindex = ht->hindex;
 	it->i = 0;
-	while (it->i < it->ht->size && it->ht->table[it->i] == NULL) {
+
+	return (isc__ht_iter_next(it));
+}
+
+static isc_result_t
+isc__ht_iter_next(isc_ht_iter_t *it) {
+	isc_ht_t *ht = it->ht;
+
+	while (it->i < ht->size[it->hindex] &&
+	       ht->table[it->hindex][it->i] == NULL) {
 		it->i++;
 	}
 
-	if (it->i == it->ht->size) {
-		return (ISC_R_NOMORE);
+	if (it->i < ht->size[it->hindex]) {
+		it->cur = ht->table[it->hindex][it->i];
+
+		return (ISC_R_SUCCESS);
 	}
 
-	it->cur = it->ht->table[it->i];
+	if (TRY_NEXTTABLE(it->hindex, ht)) {
+		it->hindex = HT_NEXTTABLE(it->hindex);
+		it->i = 0;
+		return (isc__ht_iter_next(it));
+	}
 
-	return (ISC_R_SUCCESS);
+	return (ISC_R_NOMORE);
 }
 
 isc_result_t
@@ -253,60 +505,36 @@ isc_ht_iter_next(isc_ht_iter_t *it) {
 	REQUIRE(it->cur != NULL);
 
 	it->cur = it->cur->next;
-	if (it->cur == NULL) {
-		do {
-			it->i++;
-		} while (it->i < it->ht->size && it->ht->table[it->i] == NULL);
-		if (it->i >= it->ht->size) {
-			return (ISC_R_NOMORE);
-		}
-		it->cur = it->ht->table[it->i];
+
+	if (it->cur != NULL) {
+		return (ISC_R_SUCCESS);
 	}
 
-	return (ISC_R_SUCCESS);
+	it->i++;
+
+	return (isc__ht_iter_next(it));
 }
 
 isc_result_t
 isc_ht_iter_delcurrent_next(isc_ht_iter_t *it) {
 	isc_result_t result = ISC_R_SUCCESS;
-	isc_ht_node_t *to_delete = NULL;
-	isc_ht_node_t *prev = NULL;
-	isc_ht_node_t *node = NULL;
-	uint32_t hash;
+	isc_ht_node_t *dnode = NULL;
+	uint8_t dindex;
 	isc_ht_t *ht;
+	isc_result_t dresult;
+
 	REQUIRE(it != NULL);
 	REQUIRE(it->cur != NULL);
-	to_delete = it->cur;
+
 	ht = it->ht;
+	dnode = it->cur;
+	dindex = it->hindex;
 
-	it->cur = it->cur->next;
-	if (it->cur == NULL) {
-		do {
-			it->i++;
-		} while (it->i < ht->size && ht->table[it->i] == NULL);
-		if (it->i >= ht->size) {
-			result = ISC_R_NOMORE;
-		} else {
-			it->cur = ht->table[it->i];
-		}
-	}
+	result = isc_ht_iter_next(it);
 
-	hash = isc_hash_function(to_delete->key, to_delete->keysize, true);
-	node = ht->table[hash & ht->mask];
-	while (node != to_delete) {
-		prev = node;
-		node = node->next;
-		INSIST(node != NULL);
-	}
-
-	if (prev == NULL) {
-		ht->table[hash & ht->mask] = node->next;
-	} else {
-		prev->next = node->next;
-	}
-	isc_mem_put(ht->mctx, node,
-		    offsetof(isc_ht_node_t, key) + node->keysize);
-	ht->count--;
+	dresult = isc__ht_delete(ht, dnode->key, dnode->keysize, dnode->hashval,
+				 dindex);
+	INSIST(dresult == ISC_R_SUCCESS);
 
 	return (result);
 }
@@ -331,8 +559,8 @@ isc_ht_iter_currentkey(isc_ht_iter_t *it, unsigned char **key,
 	*keysize = it->cur->keysize;
 }
 
-unsigned int
-isc_ht_count(isc_ht_t *ht) {
+size_t
+isc_ht_count(const isc_ht_t *ht) {
 	REQUIRE(ISC_HT_VALID(ht));
 
 	return (ht->count);
diff --git a/lib/isc/include/isc/ht.h b/lib/isc/include/isc/ht.h
index 1410a4a810..de347b945b 100644
--- a/lib/isc/include/isc/ht.h
+++ b/lib/isc/include/isc/ht.h
@@ -51,6 +51,7 @@ isc_ht_destroy(isc_ht_t **htp);
  *
  * Requires:
  *\li	'ht' is a valid hashtable
+ *\li   write-lock
  *
  * Returns:
  *\li	#ISC_R_NOMEMORY		-- not enough memory to create pool
@@ -58,7 +59,7 @@ isc_ht_destroy(isc_ht_t **htp);
  *\li	#ISC_R_SUCCESS		-- all is well.
  */
 isc_result_t
-isc_ht_add(isc_ht_t *ht, const unsigned char *key, uint32_t keysize,
+isc_ht_add(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize,
 	   void *value);
 
 /*%
@@ -69,27 +70,29 @@ isc_ht_add(isc_ht_t *ht, const unsigned char *key, uint32_t keysize,
  *
  * Requires:
  * \li	'ht' is a valid hashtable
+ * \li  read-lock
  *
  * Returns:
  * \li	#ISC_R_SUCCESS		-- success
  * \li	#ISC_R_NOTFOUND		-- key not found
  */
 isc_result_t
-isc_ht_find(const isc_ht_t *ht, const unsigned char *key, uint32_t keysize,
-	    void **valuep);
+isc_ht_find(const isc_ht_t *ht, const unsigned char *key,
+	    const uint32_t keysize, void **valuep);
 
 /*%
  * Delete node from hashtable
  *
  * Requires:
  *\li	ht is a valid hashtable
+ *\li   write-lock
  *
  * Returns:
  *\li	#ISC_R_NOTFOUND		-- key not found
  *\li	#ISC_R_SUCCESS		-- all is well
  */
 isc_result_t
-isc_ht_delete(isc_ht_t *ht, const unsigned char *key, uint32_t keysize);
+isc_ht_delete(isc_ht_t *ht, const unsigned char *key, const uint32_t keysize);
 
 /*%
  * Create an iterator for the hashtable; point '*itp' to it.
@@ -177,5 +180,5 @@ isc_ht_iter_currentkey(isc_ht_iter_t *it, unsigned char **key, size_t *keysize);
  * Requires:
  *\li	'ht' is a valid hashtable
  */
-unsigned int
-isc_ht_count(isc_ht_t *ht);
+size_t
+isc_ht_count(const isc_ht_t *ht);