diff --git a/json_object.c b/json_object.c
index 544542f..ad40fa9 100644
--- a/json_object.c
+++ b/json_object.c
@@ -39,18 +39,6 @@
 #error "The long long type isn't 64-bits"
 #endif
 
-#ifndef SSIZE_T_MAX
-#if SIZEOF_SSIZE_T == SIZEOF_INT
-#define SSIZE_T_MAX INT_MAX
-#elif SIZEOF_SSIZE_T == SIZEOF_LONG
-#define SSIZE_T_MAX LONG_MAX
-#elif SIZEOF_SSIZE_T == SIZEOF_LONG_LONG
-#define SSIZE_T_MAX LLONG_MAX
-#else
-#error Unable to determine size of ssize_t
-#endif
-#endif
-
 // Don't define this.  It's not thread-safe.
 /* #define REFCOUNT_DEBUG 1 */
 
@@ -589,38 +577,53 @@ int json_object_object_add_ex(struct json_object *jso, const char *const key,
 int json_object_object_add_ex_len(struct json_object *jso, const char *const key, const int len,
                                   struct json_object *const val, const unsigned opts)
 {
-	struct json_object *existing_value = NULL;
+	struct json_object *existing_value;
 	struct lh_entry *existing_entry;
 	unsigned long hash;
+	/** Required due to the `lh_get_hash` function wanting a `const struct lh_string *` */
+	const struct lh_string hashable = {.length = len, .str = {.pdata = key}};
 
 	assert(json_object_get_type(jso) == json_type_object);
 
+	// The caller must avoid creating loops in the object tree, but do a
+	// quick check anyway to make sure we're not creating a trivial loop.
+	if (jso == val)
+	{
+		return -1;
+	}
+
 	// We lookup the entry and replace the value, rather than just deleting
 	// and re-adding it, so the existing key remains valid.
-	hash = lh_get_hash(JC_OBJECT(jso)->c_object, (const void *)key);
+	hash = lh_get_hash(JC_OBJECT(jso)->c_object, (const void *)&hashable);
 	existing_entry =
 	    (opts & JSON_C_OBJECT_ADD_KEY_IS_NEW)
 	        ? NULL
 	        : lh_table_lookup_entry_w_hash(JC_OBJECT(jso)->c_object, (const void *)key, hash);
 
-	// The caller must avoid creating loops in the object tree, but do a
-	// quick check anyway to make sure we're not creating a trivial loop.
-	if (jso == val)
-		return -1;
-
-	if (!existing_entry)
+	if (existing_entry == NULL)
 	{
-		const void *const k =
-		    (opts & JSON_C_OBJECT_KEY_IS_CONSTANT) ? (const void *)key : strdup(key);
+		const struct lh_string *k = (opts & JSON_C_OBJECT_KEY_IS_CONSTANT)
+		                                ? lh_string_new_ptr(len, key)
+		                                : lh_string_new_imm(len, key);
 		if (k == NULL)
+		{
 			return -1;
-		return lh_table_insert_w_hash(JC_OBJECT(jso)->c_object, k, val, hash, opts);
+		}
+		return lh_table_insert_w_hash(JC_OBJECT(jso)->c_object, k, val, hash,
+		                              opts & ~JSON_C_OBJECT_KEY_IS_CONSTANT);
+		// `struct lh_string` always needs to be freed,
+		// so JSON_C_OBJECT_KEY_IS_CONSTANT cannot be set
+	}
+	else
+	{
+		existing_value = (json_object *)lh_entry_v(existing_entry);
+		if (existing_value)
+		{
+			json_object_put(existing_value);
+		}
+		existing_entry->v = val;
+		return 0;
 	}
-	existing_value = (json_object *)lh_entry_v(existing_entry);
-	if (existing_value)
-		json_object_put(existing_value);
-	existing_entry->v = val;
-	return 0;
 }
 
 int json_object_object_add(struct json_object *jso, const char *key, struct json_object *val)
@@ -761,7 +764,7 @@ struct json_object *json_object_new_int(int32_t i)
 
 int32_t json_object_get_int(const struct json_object *jso)
 {
-	int64_t cint64=0;
+	int64_t cint64 = 0;
 	double cdouble;
 	enum json_type o_type;
 
@@ -1751,8 +1754,8 @@ static int json_object_deep_copy_recursive(struct json_object *src, struct json_
 			/* This handles the `json_type_null` case */
 			if (!iter.val)
 				jso = NULL;
-			else if (json_object_deep_copy_recursive(iter.val, src, iter.key, UINT_MAX, &jso,
-			                                         shallow_copy) < 0)
+			else if (json_object_deep_copy_recursive(iter.val, src, iter.key, UINT_MAX,
+			                                         &jso, shallow_copy) < 0)
 			{
 				json_object_put(jso);
 				return -1;
diff --git a/json_object_private.h b/json_object_private.h
index e143b46..4f5e7c4 100644
--- a/json_object_private.h
+++ b/json_object_private.h
@@ -98,6 +98,9 @@ struct json_object_string
 
 void _json_c_set_last_err(const char *err_fmt, ...);
 
+/**
+ * The characters that can make up hexadecimal numbers
+ */
 extern const char *json_hex_chars;
 
 #ifdef __cplusplus
diff --git a/linkhash.c b/linkhash.c
index b021ef1..36dd014 100644
--- a/linkhash.c
+++ b/linkhash.c
@@ -30,6 +30,7 @@
 #endif
 
 #include "linkhash.h"
+#include "math_compat.h"
 #include "random_seed.h"
 
 /* hash functions */
@@ -485,13 +486,57 @@ static unsigned long lh_char_hash(const void *k)
 		random_seed = seed; /* potentially racy */
 #endif
 	}
-
-	return hashlittle((const char *)k, strlen((const char *)k), random_seed);
+	return hashlittle(lh_string_data((const struct lh_string *)k),
+	                  lh_string_size((const struct lh_string *)k), random_seed);
 }
 
 int lh_char_equal(const void *k1, const void *k2)
 {
-	return (strcmp((const char *)k1, (const char *)k2) == 0);
+	return lh_string_size(k1) == lh_string_size(k2) &&
+	       memcmp(lh_string_data(k1), lh_string_data(k2), lh_string_size(k1)) == 0;
+}
+
+const char *lh_string_data(const struct lh_string *str)
+{
+	return (str->length > 0) ? str->str.pdata : str->str.idata;
+}
+
+size_t lh_string_size(const struct lh_string *str)
+{
+	return (str->length > 0) ? (size_t)str->length : (size_t)(-(str->length));
+}
+
+const struct lh_string *lh_string_new_ptr(const size_t length, const char *data)
+{
+	struct lh_string *result = malloc(sizeof(struct lh_string));
+	if (result == NULL)
+	{
+		return NULL;
+	}
+	result->length = length;
+	result->str.pdata = data;
+	return result;
+}
+
+const struct lh_string *lh_string_new_imm(const size_t length, const char *data)
+{
+	struct lh_string *result;
+	if (length >
+	    SSIZE_T_MAX - (sizeof(struct lh_string) - sizeof(((struct lh_string *)NULL)->str)) - 1)
+	{
+		return NULL;
+	}
+	result =
+	    malloc(sizeof(struct lh_string) - sizeof(((struct lh_string *)NULL)->str) + length + 1);
+	if (result == NULL)
+	{
+		return NULL;
+	}
+	result->length = -length;
+	char *unconst = _LH_UNCONST(result->str.idata);
+	memcpy(unconst, data, length);
+	unconst = '\0';
+	return result;
 }
 
 struct lh_table *lh_table_new(int size, lh_entry_free_fn *free_fn, lh_hash_fn *hash_fn,
diff --git a/linkhash.h b/linkhash.h
index 0ddfa54..e304117 100644
--- a/linkhash.h
+++ b/linkhash.h
@@ -79,6 +79,34 @@ typedef unsigned long(lh_hash_fn)(const void *k);
  */
 typedef int(lh_equal_fn)(const void *k1, const void *k2);
 
+/**
+ * @brief A buffer of characters that may contain null charaters in the middle
+ *
+ * A buffer of data that can hold a normal null-terminated string
+ * (in which case `length` should just be equal to `strlen`)
+ * or a string with embedded null characters (in which case `length` reflects
+ * all the characters that make up the "string").
+ * Either way, this struct can be treated as if it contains null characters,
+ * since the `length` member should always be equal to the proper size of the
+ * buffer and the terminating null character wouldn't be included
+ * (it wouldn't be counted by strlen).
+ */
+struct lh_string
+{
+	/**
+	 * @brief Stores the length of the buffer
+	 *
+	 * If the length is positive, then `pdata` should be used.
+	 * Otherwise, idata should be used.
+	 */
+	ssize_t length;
+	union
+	{
+		const char *pdata;
+		const char idata[0];
+	} str;
+};
+
 /**
  * An entry in the hash table
  */
@@ -137,7 +165,14 @@ struct lh_table
 	 * A pointer onto the function responsible for freeing an entry.
 	 */
 	lh_entry_free_fn *free_fn;
+	/**
+	 * A function that is capable of hashing entries in this table
+	 */
 	lh_hash_fn *hash_fn;
+	/**
+	 * A function that is capable of determining if entries in this table
+	 * are equal
+	 */
 	lh_equal_fn *equal_fn;
 };
 typedef struct lh_table lh_table;
@@ -157,6 +192,41 @@ typedef struct lh_table lh_table;
 #define lh_foreach_safe(table, entry, tmp) \
 	for (entry = table->head; entry && ((tmp = entry->next) || 1); entry = tmp)
 
+/**
+ * @brief Get the data from a `struct lh_string *`
+ *
+ * @param str value to retrieve the data from
+ */
+extern const char *lh_string_data(const struct lh_string *str);
+
+/**
+ * @brief Get the length of the data stored in a `struct lh_string *`
+ *
+ * @param str value to retrieve the length of
+ */
+extern size_t lh_string_size(const struct lh_string *str);
+
+/**
+ * @brief Creates a new `struct lh_string` using the `pdata` field.
+ *
+ * This avoids unneeded copying, for cases wher ethe key is in an area of
+ * memory that will not be modified or freed until after this object is freed.
+ *
+ * @param length The length of the data located at @p data
+ * @param data The data to include
+ * @return `NULL` on error
+ */
+extern const struct lh_string *lh_string_new_ptr(const size_t length, const char *data);
+
+/**
+ * @brief Creates a new `struct lh_string` using the `idata` field.
+ *
+ * @param length The length of the data to copy into the returned value
+ * @param data The data to include and copy into the returned value
+ * @return `NULL` on error
+ */
+extern const struct lh_string *lh_string_new_imm(const size_t length, const char *data);
+
 /**
  * Create a new linkhash table.
  *
@@ -311,7 +381,7 @@ int lh_table_resize(struct lh_table *t, int new_size);
 /**
  * @deprecated Don't use this outside of linkhash.h:
  */
-#if (defined(AIX_CC) || (defined(_MSC_VER) && (_MSC_VER <= 1800)) )
+#if (defined(AIX_CC) || (defined(_MSC_VER) && (_MSC_VER <= 1800)))
 /* VS2010 can't handle inline funcs, so skip it there */
 #define _LH_INLINE
 #else
diff --git a/math_compat.h b/math_compat.h
index 2382fe1..9894776 100644
--- a/math_compat.h
+++ b/math_compat.h
@@ -40,4 +40,17 @@
 #define HAVE_DECL_NAN
 #endif
 
+#include <limits.h>
+#ifndef SSIZE_T_MAX
+#if SIZEOF_SSIZE_T == SIZEOF_INT
+#define SSIZE_T_MAX INT_MAX
+#elif SIZEOF_SSIZE_T == SIZEOF_LONG
+#define SSIZE_T_MAX LONG_MAX
+#elif SIZEOF_SSIZE_T == SIZEOF_LONG_LONG
+#define SSIZE_T_MAX LLONG_MAX
+#else
+#error Unable to determine size of ssize_t
+#endif
+#endif
+
 #endif