diff --git a/docs/02.API-REFERENCE.md b/docs/02.API-REFERENCE.md
index 1d18b611a..37cb05499 100644
--- a/docs/02.API-REFERENCE.md
+++ b/docs/02.API-REFERENCE.md
@@ -1612,13 +1612,13 @@ jerry_value_set_abort_flag (jerry_value_t *value_p);
 If the input value is an error value, then return a new reference to its referenced value.
 Otherwise, return a new reference to the value itself.
 
-*Note*: Returned value must be freed with [jerry_release_value](#jerry_release_value) 
+*Note*: Returned value must be freed with [jerry_release_value](#jerry_release_value)
 when it is no longer needed.
 
 **Prototype**
 
 ```c
-jerry_value_t 
+jerry_value_t
 jerry_get_value_without_error_flag (jerry_value_t value)
 ```
 
@@ -1630,12 +1630,12 @@ jerry_get_value_without_error_flag (jerry_value_t value)
 {
   jerry_value_t value;
   ... // create or acquire value
-  
+
   jerry_value_set_error_flag (&value);
-  
+
   jerry_value_t real_value = jerry_get_value_without_error_flag (value);
-  ... // process the real_value. Different from `jerry_value_clear_error_flag`, 
-      // the error `value` will not be automatically released after calling 
+  ... // process the real_value. Different from `jerry_value_clear_error_flag`,
+      // the error `value` will not be automatically released after calling
       // `jerry_get_value_without_error_flag`.
 
   jerry_release_value (value);
@@ -1905,6 +1905,12 @@ enough for the whole string.
 *Note*: Does not put '\0' to the end of string, the return value identifies
 the number of valid bytes in the output buffer.
 
+*Note*: If the size of the string in jerry value is larger than the size of the
+target buffer, the copy will fail. To copy a substring the
+[jerry_substring_to_char_buffer](#jerry_substring_to_char_buffer) API function
+is recommended instead.
+
+
 **Prototype**
 
 ```c
@@ -1940,6 +1946,7 @@ jerry_string_to_char_buffer (const jerry_value_t value,
 - [jerry_create_string](#jerry_create_string)
 - [jerry_get_string_size](#jerry_get_string_size)
 - [jerry_is_valid_cesu8_string](#jerry_is_valid_cesu8_string)
+- [jerry_substring_to_char_buffer](#jerry_substring_to_char_buffer)
 
 
 ## jerry_string_to_utf8_char_buffer
@@ -1954,6 +1961,11 @@ large enough for the whole string.
 *Note*: Does not put '\0' to the end of string, the return value identifies
 the number of valid bytes in the output buffer.
 
+*Note*: If the size of the string in jerry value is larger than the size of the
+target buffer, the copy will fail. To copy a substring the
+[jerry_substring_to_utf8_char_buffer](#jerry_substring_to_utf8_char_buffer)
+API function is recommended instead.
+
 **Prototype**
 
 ```c
@@ -1989,6 +2001,7 @@ jerry_string_to_utf8_char_buffer (const jerry_value_t value,
 - [jerry_create_string_from_utf8](#jerry_create_string_from_utf8)
 - [jerry_get_utf8_string_size](#jerry_get_utf8_string_size)
 - [jerry_is_valid_utf8_string](#jerry_is_valid_utf8_string)
+- [jerry_substring_to_utf8_char_buffer](#jerry_substring_to_utf8_char_buffer)
 
 
 ## jerry_substring_to_char_buffer
diff --git a/jerry-core/api/jerry.c b/jerry-core/api/jerry.c
index a2ba098c2..ae67584b9 100644
--- a/jerry-core/api/jerry.c
+++ b/jerry-core/api/jerry.c
@@ -1521,6 +1521,11 @@ jerry_get_utf8_string_length (const jerry_value_t value) /**< input string */
  *      Returns 0, if the value parameter is not a string or
  *      the buffer is not large enough for the whole string.
  *
+ * Note:
+ *      If the size of the string in jerry value is larger than the size of the
+ *      target buffer, the copy will fail.
+ *      To copy substring use jerry_substring_to_char_buffer() instead.
+ *
  * @return number of bytes, actually copied to the buffer.
  */
 jerry_size_t
@@ -1557,6 +1562,11 @@ jerry_string_to_char_buffer (const jerry_value_t value, /**< input string value
  *      Returns 0, if the value parameter is not a string or the buffer
  *      is not large enough for the whole string.
  *
+ * Note:
+ *      If the size of the string in jerry value is larger than the size of the
+ *      target buffer, the copy will fail.
+ *      To copy a substring use jerry_substring_to_utf8_char_buffer() instead.
+ *
  * @return number of bytes copied to the buffer.
  */
 jerry_size_t