diff --git a/src/dump.c b/src/dump.c
index 1baa248..7e14db4 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -263,7 +263,7 @@ static int do_dump(const json_t *json, size_t flags, int depth, hashtable_t *par
             if (!embed && dump("[", 1, data))
                 return -1;
             if (n == 0) {
-                hashtable_del(parents, key);
+                hashtable_del(parents, key, strlen(key));
                 return embed ? 0 : dump("]", 1, data);
             }
             if (dump_indent(flags, depth + 1, 0, dump, data))
@@ -284,7 +284,7 @@ static int do_dump(const json_t *json, size_t flags, int depth, hashtable_t *par
                 }
             }
 
-            hashtable_del(parents, key);
+            hashtable_del(parents, key, strlen(key));
             return embed ? 0 : dump("]", 1, data);
         }
 
@@ -311,7 +311,7 @@ static int do_dump(const json_t *json, size_t flags, int depth, hashtable_t *par
             if (!embed && dump("{", 1, data))
                 return -1;
             if (!iter) {
-                hashtable_del(parents, loop_key);
+                hashtable_del(parents, loop_key, strlen(loop_key));
                 return embed ? 0 : dump("}", 1, data);
             }
             if (dump_indent(flags, depth + 1, 0, dump, data))
@@ -392,7 +392,7 @@ static int do_dump(const json_t *json, size_t flags, int depth, hashtable_t *par
                 }
             }
 
-            hashtable_del(parents, loop_key);
+            hashtable_del(parents, loop_key, strlen(loop_key));
             return embed ? 0 : dump("}", 1, data);
         }
 
diff --git a/src/hashtable.c b/src/hashtable.c
index fd1e706..743e233 100644
--- a/src/hashtable.c
+++ b/src/hashtable.c
@@ -35,7 +35,7 @@ extern volatile uint32_t hashtable_seed;
 
 #define list_to_pair(list_)         container_of(list_, pair_t, list)
 #define ordered_list_to_pair(list_) container_of(list_, pair_t, ordered_list)
-#define hash_str(key)               ((size_t)hashlittle((key), strlen(key), hashtable_seed))
+#define hash_str(key, len)          ((size_t)hashlittle((key), len, hashtable_seed))
 
 static JSON_INLINE void list_init(list_t *list) {
     list->next = list;
@@ -69,7 +69,7 @@ static void insert_to_bucket(hashtable_t *hashtable, bucket_t *bucket, list_t *l
 }
 
 static pair_t *hashtable_find_pair(hashtable_t *hashtable, bucket_t *bucket,
-                                   const char *key, size_t hash) {
+                                   const char *key, size_t key_len, size_t hash) {
     list_t *list;
     pair_t *pair;
 
@@ -79,7 +79,8 @@ static pair_t *hashtable_find_pair(hashtable_t *hashtable, bucket_t *bucket,
     list = bucket->first;
     while (1) {
         pair = list_to_pair(list);
-        if (pair->hash == hash && strcmp(pair->key, key) == 0)
+        if (pair->hash == hash && pair->key_len == key_len &&
+            memcmp(pair->key, key, key_len) == 0)
             return pair;
 
         if (list == bucket->last)
@@ -92,7 +93,8 @@ static pair_t *hashtable_find_pair(hashtable_t *hashtable, bucket_t *bucket,
 }
 
 /* returns 0 on success, -1 if key was not found */
-static int hashtable_do_del(hashtable_t *hashtable, const char *key, size_t hash) {
+static int hashtable_do_del(hashtable_t *hashtable, const char *key, size_t key_len,
+                            size_t hash) {
     pair_t *pair;
     bucket_t *bucket;
     size_t index;
@@ -100,7 +102,7 @@ static int hashtable_do_del(hashtable_t *hashtable, const char *key, size_t hash
     index = hash & hashmask(hashtable->order);
     bucket = &hashtable->buckets[index];
 
-    pair = hashtable_find_pair(hashtable, bucket, key, hash);
+    pair = hashtable_find_pair(hashtable, bucket, key, key_len, hash);
     if (!pair)
         return -1;
 
@@ -193,7 +195,37 @@ void hashtable_close(hashtable_t *hashtable) {
     jsonp_free(hashtable->buckets);
 }
 
-int hashtable_set(hashtable_t *hashtable, const char *key, json_t *value) {
+static pair_t *init_pair(json_t *value, const char *key, size_t key_len, size_t hash) {
+    pair_t *pair;
+
+    /* offsetof(...) returns the size of pair_t without the last,
+   flexible member. This way, the correct amount is
+   allocated. */
+
+    if (key_len >= (size_t)-1 - offsetof(pair_t, key)) {
+        /* Avoid an overflow if the key is very long */
+        return NULL;
+    }
+
+    pair = jsonp_malloc(offsetof(pair_t, key) + key_len + 1);
+
+    if (!pair)
+        return NULL;
+
+    pair->hash = hash;
+    memcpy(pair->key, key, key_len);
+    pair->key[key_len] = '\0';
+    pair->key_len = key_len;
+    pair->value = value;
+
+    list_init(&pair->list);
+    list_init(&pair->ordered_list);
+
+    return pair;
+}
+
+int hashtable_set(hashtable_t *hashtable, const char *key, size_t key_len,
+                  json_t *value) {
     pair_t *pair;
     bucket_t *bucket;
     size_t hash, index;
@@ -203,35 +235,20 @@ int hashtable_set(hashtable_t *hashtable, const char *key, json_t *value) {
         if (hashtable_do_rehash(hashtable))
             return -1;
 
-    hash = hash_str(key);
+    hash = hash_str(key, key_len);
     index = hash & hashmask(hashtable->order);
     bucket = &hashtable->buckets[index];
-    pair = hashtable_find_pair(hashtable, bucket, key, hash);
+    pair = hashtable_find_pair(hashtable, bucket, key, key_len, hash);
 
     if (pair) {
         json_decref(pair->value);
         pair->value = value;
     } else {
-        /* offsetof(...) returns the size of pair_t without the last,
-           flexible member. This way, the correct amount is
-           allocated. */
+        pair = init_pair(value, key, key_len, hash);
 
-        size_t len = strlen(key);
-        if (len >= (size_t)-1 - offsetof(pair_t, key)) {
-            /* Avoid an overflow if the key is very long */
-            return -1;
-        }
-
-        pair = jsonp_malloc(offsetof(pair_t, key) + len + 1);
         if (!pair)
             return -1;
 
-        pair->hash = hash;
-        strncpy(pair->key, key, len + 1);
-        pair->value = value;
-        list_init(&pair->list);
-        list_init(&pair->ordered_list);
-
         insert_to_bucket(hashtable, bucket, &pair->list);
         list_insert(&hashtable->ordered_list, &pair->ordered_list);
 
@@ -240,24 +257,24 @@ int hashtable_set(hashtable_t *hashtable, const char *key, json_t *value) {
     return 0;
 }
 
-void *hashtable_get(hashtable_t *hashtable, const char *key) {
+void *hashtable_get(hashtable_t *hashtable, const char *key, size_t key_len) {
     pair_t *pair;
     size_t hash;
     bucket_t *bucket;
 
-    hash = hash_str(key);
+    hash = hash_str(key, key_len);
     bucket = &hashtable->buckets[hash & hashmask(hashtable->order)];
 
-    pair = hashtable_find_pair(hashtable, bucket, key, hash);
+    pair = hashtable_find_pair(hashtable, bucket, key, key_len, hash);
     if (!pair)
         return NULL;
 
     return pair->value;
 }
 
-int hashtable_del(hashtable_t *hashtable, const char *key) {
-    size_t hash = hash_str(key);
-    return hashtable_do_del(hashtable, key, hash);
+int hashtable_del(hashtable_t *hashtable, const char *key, size_t key_len) {
+    size_t hash = hash_str(key, key_len);
+    return hashtable_do_del(hashtable, key, key_len, hash);
 }
 
 void hashtable_clear(hashtable_t *hashtable) {
@@ -278,15 +295,15 @@ void *hashtable_iter(hashtable_t *hashtable) {
     return hashtable_iter_next(hashtable, &hashtable->ordered_list);
 }
 
-void *hashtable_iter_at(hashtable_t *hashtable, const char *key) {
+void *hashtable_iter_at(hashtable_t *hashtable, const char *key, size_t key_len) {
     pair_t *pair;
     size_t hash;
     bucket_t *bucket;
 
-    hash = hash_str(key);
+    hash = hash_str(key, key_len);
     bucket = &hashtable->buckets[hash & hashmask(hashtable->order)];
 
-    pair = hashtable_find_pair(hashtable, bucket, key, hash);
+    pair = hashtable_find_pair(hashtable, bucket, key, key_len, hash);
     if (!pair)
         return NULL;
 
diff --git a/src/hashtable.h b/src/hashtable.h
index 6c4845d..6defa00 100644
--- a/src/hashtable.h
+++ b/src/hashtable.h
@@ -24,6 +24,7 @@ struct hashtable_pair {
     struct hashtable_list ordered_list;
     size_t hash;
     json_t *value;
+    size_t key_len;
     char key[1];
 };
 
@@ -69,6 +70,7 @@ void hashtable_close(hashtable_t *hashtable);
  *
  * @hashtable: The hashtable object
  * @key: The key
+ * @key: The length of key
  * @serial: For addition order of keys
  * @value: The value
  *
@@ -79,27 +81,29 @@ void hashtable_close(hashtable_t *hashtable);
  *
  * Returns 0 on success, -1 on failure (out of memory).
  */
-int hashtable_set(hashtable_t *hashtable, const char *key, json_t *value);
+int hashtable_set(hashtable_t *hashtable, const char *key, size_t key_len, json_t *value);
 
 /**
  * hashtable_get - Get a value associated with a key
  *
  * @hashtable: The hashtable object
  * @key: The key
+ * @key: The length of key
  *
  * Returns value if it is found, or NULL otherwise.
  */
-void *hashtable_get(hashtable_t *hashtable, const char *key);
+void *hashtable_get(hashtable_t *hashtable, const char *key, size_t key_len);
 
 /**
  * hashtable_del - Remove a value from the hashtable
  *
  * @hashtable: The hashtable object
  * @key: The key
+ * @key: The length of key
  *
  * Returns 0 on success, or -1 if the key was not found.
  */
-int hashtable_del(hashtable_t *hashtable, const char *key);
+int hashtable_del(hashtable_t *hashtable, const char *key, size_t key_len);
 
 /**
  * hashtable_clear - Clear hashtable
@@ -132,11 +136,12 @@ void *hashtable_iter(hashtable_t *hashtable);
  *
  * @hashtable: The hashtable object
  * @key: The key that the iterator should point to
+ * @key: The length of key
  *
  * Like hashtable_iter() but returns an iterator pointing to a
  * specific key.
  */
-void *hashtable_iter_at(hashtable_t *hashtable, const char *key);
+void *hashtable_iter_at(hashtable_t *hashtable, const char *key, size_t key_len);
 
 /**
  * hashtable_iter_next - Advance an iterator
diff --git a/src/pack_unpack.c b/src/pack_unpack.c
index a89be58..04c116e 100644
--- a/src/pack_unpack.c
+++ b/src/pack_unpack.c
@@ -544,7 +544,7 @@ static int unpack_object(scanner_t *s, json_t *root, va_list *ap) {
         if (unpack(s, value, ap))
             goto out;
 
-        hashtable_set(&key_set, key, json_null());
+        hashtable_set(&key_set, key, strlen(key), json_null());
         next_token(s);
     }
 
@@ -554,6 +554,7 @@ static int unpack_object(scanner_t *s, json_t *root, va_list *ap) {
     if (root && strict == 1) {
         /* We need to check that all non optional items have been parsed */
         const char *key;
+        size_t key_len;
         /* keys_res is 1 for uninitialized, 0 for success, -1 for error. */
         int keys_res = 1;
         strbuffer_t unrecognized_keys;
@@ -562,7 +563,8 @@ static int unpack_object(scanner_t *s, json_t *root, va_list *ap) {
 
         if (gotopt || json_object_size(root) != key_set.size) {
             json_object_foreach(root, key, value) {
-                if (!hashtable_get(&key_set, key)) {
+                key_len = strlen(key);
+                if (!hashtable_get(&key_set, key, key_len)) {
                     unpacked++;
 
                     /* Save unrecognized keys for the error message */
@@ -574,7 +576,7 @@ static int unpack_object(scanner_t *s, json_t *root, va_list *ap) {
 
                     if (!keys_res)
                         keys_res =
-                            strbuffer_append_bytes(&unrecognized_keys, key, strlen(key));
+                            strbuffer_append_bytes(&unrecognized_keys, key, key_len);
                 }
             }
         }
diff --git a/src/value.c b/src/value.c
index c85a0b4..e46d14f 100644
--- a/src/value.c
+++ b/src/value.c
@@ -46,11 +46,12 @@ static JSON_INLINE void json_init(json_t *json, json_type type) {
 
 int jsonp_loop_check(hashtable_t *parents, const json_t *json, char *key,
                      size_t key_size) {
-    snprintf(key, key_size, "%p", json);
-    if (hashtable_get(parents, key))
+    size_t key_len = snprintf(key, key_size, "%p", json);
+
+    if (hashtable_get(parents, key, key_len))
         return -1;
 
-    return hashtable_set(parents, key, json_null());
+    return hashtable_set(parents, key, key_len, json_null());
 }
 
 /*** object ***/
@@ -99,7 +100,7 @@ json_t *json_object_get(const json_t *json, const char *key) {
         return NULL;
 
     object = json_to_object(json);
-    return hashtable_get(&object->hashtable, key);
+    return hashtable_get(&object->hashtable, key, strlen(key));
 }
 
 int json_object_set_new_nocheck(json_t *json, const char *key, json_t *value) {
@@ -114,7 +115,7 @@ int json_object_set_new_nocheck(json_t *json, const char *key, json_t *value) {
     }
     object = json_to_object(json);
 
-    if (hashtable_set(&object->hashtable, key, value)) {
+    if (hashtable_set(&object->hashtable, key, strlen(key), value)) {
         json_decref(value);
         return -1;
     }
@@ -138,7 +139,7 @@ int json_object_del(json_t *json, const char *key) {
         return -1;
 
     object = json_to_object(json);
-    return hashtable_del(&object->hashtable, key);
+    return hashtable_del(&object->hashtable, key, strlen(key));
 }
 
 int json_object_clear(json_t *json) {
@@ -226,7 +227,7 @@ int do_object_update_recursive(json_t *object, json_t *other, hashtable_t *paren
         }
     }
 
-    hashtable_del(parents, loop_key);
+    hashtable_del(parents, loop_key, strlen(loop_key));
 
     return res;
 }
@@ -260,7 +261,7 @@ void *json_object_iter_at(json_t *json, const char *key) {
         return NULL;
 
     object = json_to_object(json);
-    return hashtable_iter_at(&object->hashtable, key);
+    return hashtable_iter_at(&object->hashtable, key, strlen(key));
 }
 
 void *json_object_iter_next(json_t *json, void *iter) {
@@ -366,7 +367,7 @@ static json_t *json_object_deep_copy(const json_t *object, hashtable_t *parents)
     }
 
 out:
-    hashtable_del(parents, loop_key);
+    hashtable_del(parents, loop_key, strlen(loop_key));
 
     return result;
 }
@@ -651,7 +652,7 @@ static json_t *json_array_deep_copy(const json_t *array, hashtable_t *parents) {
     }
 
 out:
-    hashtable_del(parents, loop_key);
+    hashtable_del(parents, loop_key, strlen(loop_key));
 
     return result;
 }