diff --git a/src/dump.c b/src/dump.c
index 3b19c73..3589de1 100644
--- a/src/dump.c
+++ b/src/dump.c
@@ -65,24 +65,25 @@ static int dump_indent(size_t flags, int depth, int space, json_dump_callback_t
     return 0;
 }
 
-static int dump_string(const char *str, json_dump_callback_t dump, void *data, size_t flags)
+static int dump_string(const char *str, size_t len, json_dump_callback_t dump, void *data, size_t flags)
 {
-    const char *pos, *end;
+    const char *pos, *end, *lim;
     int32_t codepoint;
 
     if(dump("\"", 1, data))
         return -1;
 
     end = pos = str;
+    lim = str + len;
     while(1)
     {
         const char *text;
         char seq[13];
         int length;
 
-        while(*end)
+        while(end < lim)
         {
-            end = utf8_iterate(pos, &codepoint);
+            end = utf8_iterate(pos, lim - pos, &codepoint);
             if(!end)
                 return -1;
 
@@ -215,7 +216,7 @@ static int do_dump(const json_t *json, size_t flags, int depth,
         }
 
         case JSON_STRING:
-            return dump_string(json_string_value(json), dump, data, flags);
+            return dump_string(json_string_value(json), json_string_length(json), dump, data, flags);
 
         case JSON_ARRAY:
         {
@@ -336,7 +337,7 @@ static int do_dump(const json_t *json, size_t flags, int depth,
                     value = json_object_get(json, key);
                     assert(value);
 
-                    dump_string(key, dump, data, flags);
+                    dump_string(key, strlen(key), dump, data, flags);
                     if(dump(separator, separator_length, data) ||
                        do_dump(value, flags, depth + 1, dump, data))
                     {
@@ -372,8 +373,9 @@ static int do_dump(const json_t *json, size_t flags, int depth,
                 while(iter)
                 {
                     void *next = json_object_iter_next((json_t *)json, iter);
+                    const char *key = json_object_iter_key(iter);
 
-                    dump_string(json_object_iter_key(iter), dump, data, flags);
+                    dump_string(key, strlen(key), dump, data, flags);
                     if(dump(separator, separator_length, data) ||
                        do_dump(json_object_iter_value(iter), flags, depth + 1,
                                dump, data))
diff --git a/src/jansson.h b/src/jansson.h
index 52c8077..e76d6c3 100644
--- a/src/jansson.h
+++ b/src/jansson.h
@@ -67,23 +67,25 @@ typedef long json_int_t;
 #endif
 
 #define json_typeof(json)      ((json)->type)
-#define json_is_object(json)   (json && json_typeof(json) == JSON_OBJECT)
-#define json_is_array(json)    (json && json_typeof(json) == JSON_ARRAY)
-#define json_is_string(json)   (json && json_typeof(json) == JSON_STRING)
-#define json_is_integer(json)  (json && json_typeof(json) == JSON_INTEGER)
-#define json_is_real(json)     (json && json_typeof(json) == JSON_REAL)
+#define json_is_object(json)   ((json) && json_typeof(json) == JSON_OBJECT)
+#define json_is_array(json)    ((json) && json_typeof(json) == JSON_ARRAY)
+#define json_is_string(json)   ((json) && json_typeof(json) == JSON_STRING)
+#define json_is_integer(json)  ((json) && json_typeof(json) == JSON_INTEGER)
+#define json_is_real(json)     ((json) && json_typeof(json) == JSON_REAL)
 #define json_is_number(json)   (json_is_integer(json) || json_is_real(json))
-#define json_is_true(json)     (json && json_typeof(json) == JSON_TRUE)
-#define json_is_false(json)    (json && json_typeof(json) == JSON_FALSE)
+#define json_is_true(json)     ((json) && json_typeof(json) == JSON_TRUE)
+#define json_is_false(json)    ((json) && json_typeof(json) == JSON_FALSE)
 #define json_is_boolean(json)  (json_is_true(json) || json_is_false(json))
-#define json_is_null(json)     (json && json_typeof(json) == JSON_NULL)
+#define json_is_null(json)     ((json) && json_typeof(json) == JSON_NULL)
 
 /* construction, destruction, reference counting */
 
 json_t *json_object(void);
 json_t *json_array(void);
 json_t *json_string(const char *value);
+json_t *json_stringn(const char *value, size_t len);
 json_t *json_string_nocheck(const char *value);
+json_t *json_stringn_nocheck(const char *value, size_t len);
 json_t *json_integer(json_int_t value);
 json_t *json_real(double value);
 json_t *json_true(void);
@@ -199,16 +201,18 @@ int json_array_insert(json_t *array, size_t ind, json_t *value)
 }
 
 const char *json_string_value(const json_t *string);
+size_t json_string_length(const json_t *string);
 json_int_t json_integer_value(const json_t *integer);
 double json_real_value(const json_t *real);
 double json_number_value(const json_t *json);
 
 int json_string_set(json_t *string, const char *value);
+int json_string_setn(json_t *string, const char *value, size_t len);
 int json_string_set_nocheck(json_t *string, const char *value);
+int json_string_setn_nocheck(json_t *string, const char *value, size_t len);
 int json_integer_set(json_t *integer, json_int_t value);
 int json_real_set(json_t *real, double value);
 
-
 /* pack, unpack */
 
 json_t *json_pack(const char *fmt, ...);
diff --git a/src/jansson_private.h b/src/jansson_private.h
index 403b53a..eb51d0d 100644
--- a/src/jansson_private.h
+++ b/src/jansson_private.h
@@ -49,6 +49,7 @@ typedef struct {
 typedef struct {
     json_t json;
     char *value;
+    size_t length;
 } json_string_t;
 
 typedef struct {
@@ -64,9 +65,13 @@ typedef struct {
 #define json_to_object(json_)  container_of(json_, json_object_t, json)
 #define json_to_array(json_)   container_of(json_, json_array_t, json)
 #define json_to_string(json_)  container_of(json_, json_string_t, json)
-#define json_to_real(json_)   container_of(json_, json_real_t, json)
+#define json_to_real(json_)    container_of(json_, json_real_t, json)
 #define json_to_integer(json_) container_of(json_, json_integer_t, json)
 
+/* Create a string by taking ownership of an existing buffer */
+json_t *jsonp_stringn_nocheck_own(const char *value, size_t len);
+
+/* Error message formatting */
 void jsonp_error_init(json_error_t *error, const char *source);
 void jsonp_error_set_source(json_error_t *error, const char *source);
 void jsonp_error_set(json_error_t *error, int line, int column,
@@ -83,6 +88,7 @@ void* jsonp_malloc(size_t size);
 void jsonp_free(void *ptr);
 char *jsonp_strndup(const char *str, size_t length);
 char *jsonp_strdup(const char *str);
+char *jsonp_strndup(const char *str, size_t len);
 
 /* Windows compatibility */
 #ifdef _WIN32
diff --git a/src/load.c b/src/load.c
index c5536f5..340b748 100644
--- a/src/load.c
+++ b/src/load.c
@@ -63,7 +63,10 @@ typedef struct {
     strbuffer_t saved_text;
     int token;
     union {
-        char *string;
+        struct {
+            char *val;
+            size_t len;
+        } string;
         json_int_t integer;
         double real;
     } value;
@@ -279,6 +282,13 @@ static void lex_save_cached(lex_t *lex)
     }
 }
 
+static void lex_free_string(lex_t *lex)
+{
+    jsonp_free(lex->value.string.val);
+    lex->value.string.val = NULL;
+    lex->value.string.len = 0;
+}
+
 /* assumes that str points to 'u' plus at least 4 valid hex digits */
 static int32_t decode_unicode_escape(const char *str)
 {
@@ -297,7 +307,7 @@ static int32_t decode_unicode_escape(const char *str)
         else if(l_isupper(c))
             value += c - 'A' + 10;
         else
-            assert(0);
+            return -1;
     }
 
     return value;
@@ -310,7 +320,7 @@ static void lex_scan_string(lex_t *lex, json_error_t *error)
     char *t;
     int i;
 
-    lex->value.string = NULL;
+    lex->value.string.val = NULL;
     lex->token = TOKEN_INVALID;
 
     c = lex_get_save(lex, error);
@@ -365,14 +375,12 @@ static void lex_scan_string(lex_t *lex, json_error_t *error)
          - two \uXXXX escapes (length 12) forming an UTF-16 surrogate pair
            are converted to 4 bytes
     */
-    lex->value.string = jsonp_malloc(lex->saved_text.length + 1);
-    if(!lex->value.string) {
+    t = jsonp_malloc(lex->saved_text.length + 1);
+    if(!t) {
         /* this is not very nice, since TOKEN_INVALID is returned */
         goto out;
     }
-
-    /* the target */
-    t = lex->value.string;
+    lex->value.string.val = t;
 
     /* + 1 to skip the " */
     p = strbuffer_value(&lex->saved_text) + 1;
@@ -381,17 +389,24 @@ static void lex_scan_string(lex_t *lex, json_error_t *error)
         if(*p == '\\') {
             p++;
             if(*p == 'u') {
-                char buffer[4];
-                int length;
+                size_t length;
                 int32_t value;
 
                 value = decode_unicode_escape(p);
+                if(value < 0) {
+                    error_set(error, lex, "invalid Unicode escape '%.6s'", p - 1);
+                    goto out;
+                }
                 p += 5;
 
                 if(0xD800 <= value && value <= 0xDBFF) {
                     /* surrogate pair */
                     if(*p == '\\' && *(p + 1) == 'u') {
                         int32_t value2 = decode_unicode_escape(++p);
+                        if(value2 < 0) {
+                            error_set(error, lex, "invalid Unicode escape '%.6s'", p - 1);
+                            goto out;
+                        }
                         p += 5;
 
                         if(0xDC00 <= value2 && value2 <= 0xDFFF) {
@@ -420,16 +435,9 @@ static void lex_scan_string(lex_t *lex, json_error_t *error)
                     error_set(error, lex, "invalid Unicode '\\u%04X'", value);
                     goto out;
                 }
-                else if(value == 0)
-                {
-                    error_set(error, lex, "\\u0000 is not allowed");
-                    goto out;
-                }
 
-                if(utf8_encode(value, buffer, &length))
+                if(utf8_encode(value, t, &length))
                     assert(0);
-
-                memcpy(t, buffer, length);
                 t += length;
             }
             else {
@@ -451,11 +459,12 @@ static void lex_scan_string(lex_t *lex, json_error_t *error)
             *(t++) = *(p++);
     }
     *t = '\0';
+    lex->value.string.len = t - lex->value.string.val;
     lex->token = TOKEN_STRING;
     return;
 
 out:
-    jsonp_free(lex->value.string);
+    lex_free_string(lex);
 }
 
 #ifndef JANSSON_USING_CMAKE /* disabled if using cmake */
@@ -571,10 +580,8 @@ static int lex_scan(lex_t *lex, json_error_t *error)
 
     strbuffer_clear(&lex->saved_text);
 
-    if(lex->token == TOKEN_STRING) {
-        jsonp_free(lex->value.string);
-        lex->value.string = NULL;
-    }
+    if(lex->token == TOKEN_STRING)
+        lex_free_string(lex);
 
     c = lex_get(lex, error);
     while(c == ' ' || c == '\t' || c == '\n' || c == '\r')
@@ -635,13 +642,14 @@ out:
     return lex->token;
 }
 
-static char *lex_steal_string(lex_t *lex)
+static char *lex_steal_string(lex_t *lex, size_t *out_len)
 {
     char *result = NULL;
-    if(lex->token == TOKEN_STRING)
-    {
-        result = lex->value.string;
-        lex->value.string = NULL;
+    if(lex->token == TOKEN_STRING) {
+        result = lex->value.string.val;
+        *out_len = lex->value.string.len;
+        lex->value.string.val = NULL;
+        lex->value.string.len = 0;
     }
     return result;
 }
@@ -659,7 +667,7 @@ static int lex_init(lex_t *lex, get_func get, void *data)
 static void lex_close(lex_t *lex)
 {
     if(lex->token == TOKEN_STRING)
-        jsonp_free(lex->value.string);
+        lex_free_string(lex);
     strbuffer_close(&lex->saved_text);
 }
 
@@ -680,6 +688,7 @@ static json_t *parse_object(lex_t *lex, size_t flags, json_error_t *error)
 
     while(1) {
         char *key;
+        size_t len;
         json_t *value;
 
         if(lex->token != TOKEN_STRING) {
@@ -687,9 +696,14 @@ static json_t *parse_object(lex_t *lex, size_t flags, json_error_t *error)
             goto error;
         }
 
-        key = lex_steal_string(lex);
+        key = lex_steal_string(lex, &len);
         if(!key)
             return NULL;
+        if (memchr(key, len, '\0')) {
+            jsonp_free(key);
+            error_set(error, lex, "nul char in object key not supported");
+            goto error;
+        }
 
         if(flags & JSON_REJECT_DUPLICATES) {
             if(json_object_get(object, key)) {
@@ -788,7 +802,11 @@ static json_t *parse_value(lex_t *lex, size_t flags, json_error_t *error)
 
     switch(lex->token) {
         case TOKEN_STRING: {
-            json = json_string_nocheck(lex->value.string);
+            json = jsonp_stringn_nocheck_own(lex->value.string.val, lex->value.string.len);
+            if(json) {
+                lex->value.string.val = NULL;
+                lex->value.string.len = 0;
+            }
             break;
         }
 
diff --git a/src/memory.c b/src/memory.c
index eb6cec5..e6da96e 100644
--- a/src/memory.c
+++ b/src/memory.c
@@ -12,6 +12,10 @@
 #include "jansson.h"
 #include "jansson_private.h"
 
+/* C89 allows these to be macros */
+#undef malloc
+#undef free
+
 /* memory function pointers */
 static json_malloc_t do_malloc = malloc;
 static json_free_t do_free = free;
@@ -34,18 +38,19 @@ void jsonp_free(void *ptr)
 
 char *jsonp_strdup(const char *str)
 {
-    char *new_str;
-    size_t len;
+    return jsonp_strndup(str, strlen(str));
+}
 
-    len = strlen(str);
-    if(len == (size_t)-1)
-        return NULL;
+char *jsonp_strndup(const char *str, size_t len)
+{
+    char *new_str;
 
     new_str = jsonp_malloc(len + 1);
     if(!new_str)
         return NULL;
 
-    memcpy(new_str, str, len + 1);
+    memcpy(new_str, str, len);
+    new_str[len] = '\0';
     return new_str;
 }
 
diff --git a/src/pack_unpack.c b/src/pack_unpack.c
index 0d932f7..b19097d 100644
--- a/src/pack_unpack.c
+++ b/src/pack_unpack.c
@@ -125,19 +125,18 @@ static json_t *pack(scanner_t *s, va_list *ap);
 /* ours will be set to 1 if jsonp_free() must be called for the result
    afterwards */
 static char *read_string(scanner_t *s, va_list *ap,
-                         const char *purpose, int *ours)
+                         const char *purpose, size_t *out_len, int *ours)
 {
     char t;
     strbuffer_t strbuff;
     const char *str;
     size_t length;
-    char *result;
 
     next_token(s);
     t = token(s);
     prev_token(s);
 
-    if(t != '#' && t != '+') {
+    if(t != '#' && t != '%' && t != '+') {
         /* Optimize the simple case */
         str = va_arg(*ap, const char *);
 
@@ -146,11 +145,14 @@ static char *read_string(scanner_t *s, va_list *ap,
             return NULL;
         }
 
-        if(!utf8_check_string(str, -1)) {
+        length = strlen(str);
+
+        if(!utf8_check_string(str, length)) {
             set_error(s, "<args>", "Invalid UTF-8 %s", purpose);
             return NULL;
         }
 
+        *out_len = length;
         *ours = 0;
         return (char *)str;
     }
@@ -170,6 +172,9 @@ static char *read_string(scanner_t *s, va_list *ap,
         if(token(s) == '#') {
             length = va_arg(*ap, int);
         }
+        else if(token(s) == '%') {
+            length = va_arg(*ap, size_t);
+        }
         else {
             prev_token(s);
             length = strlen(str);
@@ -188,15 +193,15 @@ static char *read_string(scanner_t *s, va_list *ap,
         }
     }
 
-    result = strbuffer_steal_value(&strbuff);
-
-    if(!utf8_check_string(result, -1)) {
+    if(!utf8_check_string(strbuff.value, strbuff.length)) {
         set_error(s, "<args>", "Invalid UTF-8 %s", purpose);
+        strbuffer_close(&strbuff);
         return NULL;
     }
 
+    *out_len = strbuff.length;
     *ours = 1;
-    return result;
+    return strbuffer_steal_value(&strbuff);
 }
 
 static json_t *pack_object(scanner_t *s, va_list *ap)
@@ -206,6 +211,7 @@ static json_t *pack_object(scanner_t *s, va_list *ap)
 
     while(token(s) != '}') {
         char *key;
+        size_t len;
         int ours;
         json_t *value;
 
@@ -219,15 +225,19 @@ static json_t *pack_object(scanner_t *s, va_list *ap)
             goto error;
         }
 
-        key = read_string(s, ap, "object key", &ours);
+        key = read_string(s, ap, "object key", &len, &ours);
         if(!key)
             goto error;
 
         next_token(s);
 
         value = pack(s, ap);
-        if(!value)
+        if(!value) {
+            if(ours)
+                jsonp_free(key);
+
             goto error;
+        }
 
         if(json_object_set_new_nocheck(object, key, value)) {
             if(ours)
@@ -290,20 +300,20 @@ static json_t *pack(scanner_t *s, va_list *ap)
         case '[':
             return pack_array(s, ap);
 
-        case 's': { /* string */
+        case 's': /* string */
+        {
             char *str;
+            size_t len;
             int ours;
-            json_t *result;
 
-            str = read_string(s, ap, "string", &ours);
+            str = read_string(s, ap, "string", &len, &ours);
             if(!str)
                 return NULL;
 
-            result = json_string_nocheck(str);
-            if(ours)
-                jsonp_free(str);
-
-            return result;
+            if (ours)
+                return jsonp_stringn_nocheck_own(str, len);
+            else
+                return json_stringn_nocheck(str, len);
         }
 
         case 'n': /* null */
@@ -523,16 +533,32 @@ static int unpack(scanner_t *s, json_t *root, va_list *ap)
             }
 
             if(!(s->flags & JSON_VALIDATE_ONLY)) {
-                const char **target;
+                const char **str_target;
+                size_t *len_target = NULL;
 
-                target = va_arg(*ap, const char **);
-                if(!target) {
+                str_target = va_arg(*ap, const char **);
+                if(!str_target) {
                     set_error(s, "<args>", "NULL string argument");
                     return -1;
                 }
 
-                if(root)
-                    *target = json_string_value(root);
+                next_token(s);
+
+                if(token(s) == '%') {
+                    len_target = va_arg(*ap, size_t *);
+                    if(!len_target) {
+                        set_error(s, "<args>", "NULL string length argument");
+                        return -1;
+                    }
+                }
+                else
+                    prev_token(s);
+
+                if(root) {
+                    *str_target = json_string_value(root);
+                    if(len_target)
+                        *len_target = json_string_length(root);
+                }
             }
             return 0;
 
diff --git a/src/utf.c b/src/utf.c
index 65b849b..0a2ba9b 100644
--- a/src/utf.c
+++ b/src/utf.c
@@ -8,7 +8,7 @@
 #include <string.h>
 #include "utf.h"
 
-int utf8_encode(int32_t codepoint, char *buffer, int *size)
+int utf8_encode(int32_t codepoint, char *buffer, size_t *size)
 {
     if(codepoint < 0)
         return -1;
@@ -44,7 +44,7 @@ int utf8_encode(int32_t codepoint, char *buffer, int *size)
     return 0;
 }
 
-int utf8_check_first(char byte)
+size_t utf8_check_first(char byte)
 {
     unsigned char u = (unsigned char)byte;
 
@@ -80,9 +80,9 @@ int utf8_check_first(char byte)
     }
 }
 
-int utf8_check_full(const char *buffer, int size, int32_t *codepoint)
+size_t utf8_check_full(const char *buffer, size_t size, int32_t *codepoint)
 {
-    int i;
+    size_t i;
     int32_t value = 0;
     unsigned char u = (unsigned char)buffer[0];
 
@@ -136,12 +136,12 @@ int utf8_check_full(const char *buffer, int size, int32_t *codepoint)
     return 1;
 }
 
-const char *utf8_iterate(const char *buffer, int32_t *codepoint)
+const char *utf8_iterate(const char *buffer, size_t bufsize, int32_t *codepoint)
 {
-    int count;
+    size_t count;
     int32_t value;
 
-    if(!*buffer)
+    if(!bufsize)
         return buffer;
 
     count = utf8_check_first(buffer[0]);
@@ -152,7 +152,7 @@ const char *utf8_iterate(const char *buffer, int32_t *codepoint)
         value = (unsigned char)buffer[0];
     else
     {
-        if(!utf8_check_full(buffer, count, &value))
+        if(count > bufsize || !utf8_check_full(buffer, count, &value))
             return NULL;
     }
 
@@ -162,16 +162,13 @@ const char *utf8_iterate(const char *buffer, int32_t *codepoint)
     return buffer + count;
 }
 
-int utf8_check_string(const char *string, int length)
+int utf8_check_string(const char *string, size_t length)
 {
-    int i;
-
-    if(length == -1)
-        length = strlen(string);
+    size_t i;
 
     for(i = 0; i < length; i++)
     {
-        int count = utf8_check_first(string[i]);
+        size_t count = utf8_check_first(string[i]);
         if(count == 0)
             return 0;
         else if(count > 1)
diff --git a/src/utf.h b/src/utf.h
index cb10c24..1409865 100644
--- a/src/utf.h
+++ b/src/utf.h
@@ -28,12 +28,12 @@ typedef int int32_t;
 
 #endif /* HAVE_CONFIG_H */
 
-int utf8_encode(int codepoint, char *buffer, int *size);
+int utf8_encode(int codepoint, char *buffer, size_t *size);
 
-int utf8_check_first(char byte);
-int utf8_check_full(const char *buffer, int size, int32_t *codepoint);
-const char *utf8_iterate(const char *buffer, int32_t *codepoint);
+size_t utf8_check_first(char byte);
+size_t utf8_check_full(const char *buffer, size_t size, int32_t *codepoint);
+const char *utf8_iterate(const char *buffer, size_t size, int32_t *codepoint);
 
-int utf8_check_string(const char *string, int length);
+int utf8_check_string(const char *string, size_t length);
 
 #endif
diff --git a/src/value.c b/src/value.c
index 582849b..1b69904 100644
--- a/src/value.c
+++ b/src/value.c
@@ -108,7 +108,7 @@ int json_object_set_new_nocheck(json_t *json, const char *key, json_t *value)
 
 int json_object_set_new(json_t *json, const char *key, json_t *value)
 {
-    if(!key || !utf8_check_string(key, -1))
+    if(!key || !utf8_check_string(key, strlen(key)))
     {
         json_decref(value);
         return -1;
@@ -620,33 +620,68 @@ static json_t *json_array_deep_copy(const json_t *array)
 
 /*** string ***/
 
-json_t *json_string_nocheck(const char *value)
+static json_t *string_create(const char *value, size_t len, int own)
 {
+    char *v;
     json_string_t *string;
 
     if(!value)
         return NULL;
 
-    string = jsonp_malloc(sizeof(json_string_t));
-    if(!string)
-        return NULL;
-    json_init(&string->json, JSON_STRING);
+    if(own)
+        v = (char *)value;
+    else {
+        v = jsonp_strndup(value, len);
+        if(!v)
+            return NULL;
+    }
 
-    string->value = jsonp_strdup(value);
-    if(!string->value) {
-        jsonp_free(string);
+    string = jsonp_malloc(sizeof(json_string_t));
+    if(!string) {
+        if(!own)
+            jsonp_free(v);
         return NULL;
     }
+    json_init(&string->json, JSON_STRING);
+    string->value = v;
+    string->length = len;
 
     return &string->json;
 }
 
-json_t *json_string(const char *value)
+json_t *json_string_nocheck(const char *value)
 {
-    if(!value || !utf8_check_string(value, -1))
+    if(!value)
         return NULL;
 
-    return json_string_nocheck(value);
+    return string_create(value, strlen(value), 0);
+}
+
+json_t *json_stringn_nocheck(const char *value, size_t len)
+{
+    return string_create(value, len, 0);
+}
+
+/* this is private; "steal" is not a public API concept */
+json_t *jsonp_stringn_nocheck_own(const char *value, size_t len)
+{
+    return string_create(value, len, 1);
+}
+
+json_t *json_string(const char *value)
+{
+    if(!value)
+        return NULL;
+
+    return json_stringn(value, strlen(value));
+}
+
+json_t *json_stringn(const char *value, size_t len)
+{
+    if(!value || !utf8_check_string(value, len))
+        return NULL;
+
+    return json_stringn_nocheck(value, len);
 }
 
 const char *json_string_value(const json_t *json)
@@ -657,7 +692,23 @@ const char *json_string_value(const json_t *json)
     return json_to_string(json)->value;
 }
 
+size_t json_string_length(const json_t *json)
+{
+    if(!json_is_string(json))
+        return 0;
+
+    return json_to_string(json)->length;
+}
+
 int json_string_set_nocheck(json_t *json, const char *value)
+{
+    if(!value)
+        return -1;
+
+    return json_string_setn_nocheck(json, value, strlen(value));
+}
+
+int json_string_setn_nocheck(json_t *json, const char *value, size_t len)
 {
     char *dup;
     json_string_t *string;
@@ -665,7 +716,7 @@ int json_string_set_nocheck(json_t *json, const char *value)
     if(!json_is_string(json) || !value)
         return -1;
 
-    dup = jsonp_strdup(value);
+    dup = jsonp_strndup(value, len);
     if(!dup)
         return -1;
 
@@ -678,10 +729,18 @@ int json_string_set_nocheck(json_t *json, const char *value)
 
 int json_string_set(json_t *json, const char *value)
 {
-    if(!value || !utf8_check_string(value, -1))
+    if(!value)
         return -1;
 
-    return json_string_set_nocheck(json, value);
+    return json_string_setn(json, value, strlen(value));
+}
+
+int json_string_setn(json_t *json, const char *value, size_t len)
+{
+    if(!value || !utf8_check_string(value, len))
+        return -1;
+
+    return json_string_setn_nocheck(json, value, len);
 }
 
 static void json_delete_string(json_string_t *string)
@@ -692,12 +751,25 @@ static void json_delete_string(json_string_t *string)
 
 static int json_string_equal(json_t *string1, json_t *string2)
 {
-    return strcmp(json_string_value(string1), json_string_value(string2)) == 0;
+    json_string_t *s1, *s2;
+
+    if(!json_is_string(string1) || !json_is_string(string2))
+        return 0;
+
+    s1 = json_to_string(string1);
+    s2 = json_to_string(string2);
+    return s1->length == s2->length && !memcmp(s1->value, s2->value, s1->length);
 }
 
 static json_t *json_string_copy(const json_t *string)
 {
-    return json_string_nocheck(json_string_value(string));
+    json_string_t *s;
+
+    if(!json_is_string(string))
+        return NULL;
+
+    s = json_to_string(string);
+    return json_stringn_nocheck(s->value, s->length);
 }
 
 
diff --git a/test/suites/api/test_pack.c b/test/suites/api/test_pack.c
index b6ac2e5..348d8b2 100644
--- a/test/suites/api/test_pack.c
+++ b/test/suites/api/test_pack.c
@@ -83,7 +83,7 @@ static void run_tests()
         fail("json_pack string refcount failed");
     json_decref(value);
 
-    /* string and length */
+    /* string and length (int) */
     value = json_pack("s#", "test asdf", 4);
     if(!json_is_string(value) || strcmp("test", json_string_value(value)))
         fail("json_pack string and length failed");
@@ -91,14 +91,30 @@ static void run_tests()
         fail("json_pack string and length refcount failed");
     json_decref(value);
 
-    /* string and length, non-NUL terminated string */
-    value = json_pack("s#", buffer, 4);
+    /* string and length (size_t) */
+    value = json_pack("s%", "test asdf", (size_t)4);
     if(!json_is_string(value) || strcmp("test", json_string_value(value)))
         fail("json_pack string and length failed");
     if(value->refcount != (size_t)1)
         fail("json_pack string and length refcount failed");
     json_decref(value);
 
+    /* string and length (int), non-NUL terminated string */
+    value = json_pack("s#", buffer, 4);
+    if(!json_is_string(value) || strcmp("test", json_string_value(value)))
+        fail("json_pack string and length (int) failed");
+    if(value->refcount != (size_t)1)
+        fail("json_pack string and length (int) refcount failed");
+    json_decref(value);
+
+    /* string and length (size_t), non-NUL terminated string */
+    value = json_pack("s%", buffer, (size_t)4);
+    if(!json_is_string(value) || strcmp("test", json_string_value(value)))
+        fail("json_pack string and length (size_t) failed");
+    if(value->refcount != (size_t)1)
+        fail("json_pack string and length (size_t) refcount failed");
+    json_decref(value);
+
     /* string concatenation */
     value = json_pack("s++", "te", "st", "ing");
     if(!json_is_string(value) || strcmp("testing", json_string_value(value)))
@@ -107,12 +123,20 @@ static void run_tests()
         fail("json_pack string concatenation refcount failed");
     json_decref(value);
 
-    /* string concatenation and length */
+    /* string concatenation and length (int) */
     value = json_pack("s#+#+", "test", 1, "test", 2, "test");
     if(!json_is_string(value) || strcmp("ttetest", json_string_value(value)))
-        fail("json_pack string concatenation and length failed");
+        fail("json_pack string concatenation and length (int) failed");
     if(value->refcount != (size_t)1)
-        fail("json_pack string concatenation and length refcount failed");
+        fail("json_pack string concatenation and length (int) refcount failed");
+    json_decref(value);
+
+    /* string concatenation and length (size_t) */
+    value = json_pack("s%+%+", "test", (size_t)1, "test", (size_t)2, "test");
+    if(!json_is_string(value) || strcmp("ttetest", json_string_value(value)))
+        fail("json_pack string concatenation and length (size_t) failed");
+    if(value->refcount != (size_t)1)
+        fail("json_pack string concatenation and length (size_t) refcount failed");
     json_decref(value);
 
     /* empty object */
diff --git a/test/suites/api/test_unpack.c b/test/suites/api/test_unpack.c
index bec8666..7f049dd 100644
--- a/test/suites/api/test_unpack.c
+++ b/test/suites/api/test_unpack.c
@@ -17,6 +17,7 @@ static void run_tests()
     int i1, i2, i3;
     json_int_t I1;
     int rv;
+    size_t z;
     double f;
     char *s;
 
@@ -81,6 +82,13 @@ static void run_tests()
         fail("json_unpack string failed");
     json_decref(j);
 
+    /* string with length (size_t) */
+    j = json_string("foo");
+    rv = json_unpack(j, "s%", &s, &z);
+    if(rv || strcmp(s, "foo") || z != 3)
+        fail("json_unpack string with length (size_t) failed");
+    json_decref(j);
+
     /* empty object */
     j = json_object();
     if(json_unpack(j, "{}"))
diff --git a/test/suites/invalid/escaped-null-byte-in-string/error b/test/suites/invalid/escaped-null-byte-in-string/error
deleted file mode 100644
index 9795f18..0000000
--- a/test/suites/invalid/escaped-null-byte-in-string/error
+++ /dev/null
@@ -1,2 +0,0 @@
-1 33 33
-\u0000 is not allowed
diff --git a/test/suites/invalid/escaped-null-byte-in-string/input b/test/suites/invalid/escaped-null-byte-in-string/input
deleted file mode 100644
index 22ae82b..0000000
--- a/test/suites/invalid/escaped-null-byte-in-string/input
+++ /dev/null
@@ -1 +0,0 @@
-["\u0000 (null byte not allowed)"]
diff --git a/test/suites/valid/escaped-null-byte-in-string/input b/test/suites/valid/escaped-null-byte-in-string/input
new file mode 100644
index 0000000..20bc990
--- /dev/null
+++ b/test/suites/valid/escaped-null-byte-in-string/input
@@ -0,0 +1 @@
+["null char \u0000 in string"]
\ No newline at end of file
diff --git a/test/suites/valid/escaped-null-byte-in-string/output b/test/suites/valid/escaped-null-byte-in-string/output
new file mode 100644
index 0000000..20bc990
--- /dev/null
+++ b/test/suites/valid/escaped-null-byte-in-string/output
@@ -0,0 +1 @@
+["null char \u0000 in string"]
\ No newline at end of file