diff --git a/docs/02.API-REFERENCE.md b/docs/02.API-REFERENCE.md
index 9d16c64b12..69103a9ee3 100644
--- a/docs/02.API-REFERENCE.md
+++ b/docs/02.API-REFERENCE.md
@@ -1233,6 +1233,7 @@ jerry_get_string_size (const jerry_value_t value);
 
 - [jerry_create_string](#jerry_create_string)
 - [jerry_get_string_length](#jerry_get_string_length)
+- [jerry_is_valid_cesu8_string](#jerry_is_valid_cesu8_string)
 
 
 ## jerry_get_utf8_string_size
@@ -1272,6 +1273,8 @@ jerry_get_utf8_string_size (const jerry_value_t value);
 
 - [jerry_create_string_from_utf8](#jerry_create_string_from_utf8)
 - [jerry_get_utf8_string_length](#jerry_get_utf8_string_length)
+- [jerry_is_valid_utf8_string](#jerry_is_valid_utf8_string)
+
 
 ## jerry_get_string_length
 
@@ -1308,6 +1311,8 @@ jerry_get_string_length (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_get_utf8_string_length
 
@@ -1347,6 +1352,8 @@ jerry_get_utf8_string_length (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_string_to_char_buffer
 
@@ -1394,6 +1401,8 @@ 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_string_to_utf8_char_buffer
 
@@ -1441,6 +1450,8 @@ 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_char_buffer
 
@@ -1496,6 +1507,8 @@ jerry_substring_to_char_buffer (const jerry_value_t value,
 - [jerry_create_string](#jerry_create_string)
 - [jerry_get_string_size](#jerry_get_string_size)
 - [jerry_get_string_length](#jerry_get_string_length)
+- [jerry_is_valid_cesu8_string](#jerry_is_valid_cesu8_string)
+
 
 ## jerry_substring_to_utf8_char_buffer
 
@@ -1548,9 +1561,12 @@ jerry_substring_to_utf8_char_buffer (const jerry_value_t value,
 
 **See also**
 
-- [jerry_create_string_from_utf8](#jerry_create_string)
+- [jerry_create_string_from_utf8](#jerry_create_string_from_utf8)
 - [jerry_get_utf8_string_size](#jerry_get_utf8_string_size)
 - [jerry_get_utf8_string_length](#jerry_get_utf8_string_length)
+- [jerry_is_valid_utf8_string](#jerry_is_valid_utf8_string)
+
+
 # Functions for array object values
 
 ## jerry_get_array_length
@@ -2260,6 +2276,7 @@ jerry_create_string (const jerry_char_t *str_p);
 
 **See also**
 
+- [jerry_is_valid_cesu8_string](#jerry_is_valid_cesu8_string)
 - [jerry_create_string_sz](#jerry_create_string_sz)
 
 
@@ -2298,8 +2315,10 @@ jerry_create_string_sz (const jerry_char_t *str_p,
 
 **See also**
 
+- [jerry_is_valid_cesu8_string](#jerry_is_valid_cesu8_string)
 - [jerry_create_string](#jerry_create_string)
 
+
 ## jerry_create_string_from_utf8
 
 **Summary**
@@ -2333,6 +2352,7 @@ jerry_create_string_from_utf8 (const jerry_char_t *str_p);
 
 **See also**
 
+- [jerry_is_valid_utf8_string](#jerry_is_valid_utf8_string)
 - [jerry_create_string_sz_from_utf8](#jerry_create_string_sz_from_utf8)
 
 
@@ -2373,8 +2393,10 @@ jerry_create_string_sz (const jerry_char_t *str_p,
 
 **See also**
 
+- [jerry_is_valid_utf8_string](#jerry_is_valid_utf8_string)
 - [jerry_create_string_from_utf8](#jerry_create_string_from_utf8)
 
+
 ## jerry_create_undefined
 
 **Summary**
@@ -3287,6 +3309,99 @@ bool foreach_function (const jerry_value_t prop_name,
 - [jerry_object_property_foreach_t](#jerry_object_property_foreach_t)
 
 
+# Input validator functions
+
+## jerry_is_valid_utf8_string
+
+**Summary**
+
+Validate UTF-8 string.
+
+**Prototype**
+
+```c
+bool
+jerry_is_valid_utf8_string (const jerry_char_t *utf8_buf_p, /**< UTF-8 string */
+                            jerry_size_t buf_size) /**< string size */
+```
+
+- `utf8_buf_p` - UTF-8 input string
+- `buf_size` - input string size
+
+**Example**
+
+```c
+{
+  const jerry_char_t script[] = "print ('Hello, World!');";
+  size_t script_size = strlen ((const char *) script);
+
+  if (jerry_is_valid_utf8_string (script, (jerry_size_t) script_size))
+  {
+    jerry_run_simple (script, script_size, JERRY_INIT_EMPTY);
+  }
+}
+```
+
+**See also**
+
+- [jerry_run_simple](#jerry_run_simple)
+- [jerry_create_string_from_utf8](#jerry_create_string_from_utf8)
+- [jerry_create_string_sz_from_utf8](#jerry_create_string_sz_from_utf8)
+- [jerry_get_utf8_string_size](#jerry_get_utf8_string_size)
+- [jerry_get_utf8_string_length](#jerry_get_utf8_string_length)
+- [jerry_string_to_utf8_char_buffer](#jerry_string_to_utf8_char_buffer)
+- [jerry_substring_to_utf8_char_buffer](#jerry_substring_to_utf8_char_buffer)
+
+## jerry_is_valid_cesu8_string
+
+**Summary**
+
+Validate CESU-8 string.
+
+**Prototype**
+
+```c
+bool
+jerry_is_valid_cesu8_string (const jerry_char_t *cesu8_buf_p, /**< CESU-8 string */
+                             jerry_size_t buf_size) /**< string size */
+```
+
+- `cesu8_buf_p` - CESU-8 input string
+- `buf_size` - input string size
+
+**Example**
+
+```c
+{
+  jerry_init (JERRY_INIT_EMPTY);
+
+  const jerry_char_t script[] = "Hello, World!";
+  size_t script_size = strlen ((const char *) script);
+
+  if (jerry_is_valid_cesu8_string (script, (jerry_size_t) script_size))
+  {
+    jerry_value_t string_value = jerry_create_string_sz (script,
+                                                         (jerry_size_t) script_size));
+
+    ... // usage of string_value
+
+    jerry_release_value (string_value);
+  }
+
+  jerry_cleanup ();
+}
+```
+
+**See also**
+
+- [jerry_create_string](#jerry_create_string)
+- [jerry_create_string_sz](#jerry_create_string_sz)
+- [jerry_get_string_size](#jerry_get_string_size)
+- [jerry_get_string_length](#jerry_get_string_length)
+- [jerry_string_to_char_buffer](#jerry_string_to_char_buffer)
+- [jerry_substring_to_char_buffer](#jerry_substring_to_char_buffer)
+
+
 # Snapshot functions
 
 ## jerry_parse_and_save_snapshot
diff --git a/jerry-core/ecma/base/ecma-helpers-string.c b/jerry-core/ecma/base/ecma-helpers-string.c
index 09992faf98..2af48ad1d1 100644
--- a/jerry-core/ecma/base/ecma-helpers-string.c
+++ b/jerry-core/ecma/base/ecma-helpers-string.c
@@ -151,7 +151,7 @@ ecma_new_ecma_string_from_utf8 (const lit_utf8_byte_t *string_p, /**< utf-8 stri
                                 lit_utf8_size_t string_size) /**< string size */
 {
   JERRY_ASSERT (string_p != NULL || string_size == 0);
-  JERRY_ASSERT (lit_is_cesu8_string_valid (string_p, string_size));
+  JERRY_ASSERT (lit_is_valid_cesu8_string (string_p, string_size));
 
   lit_magic_string_id_t magic_string_id = lit_is_utf8_string_magic (string_p, string_size);
 
@@ -269,7 +269,7 @@ ecma_new_ecma_string_from_utf8_converted_to_cesu8 (const lit_utf8_byte_t *string
   {
     converted_string_size += string_size;
 
-    JERRY_ASSERT (lit_is_utf8_string_valid (string_p, string_size));
+    JERRY_ASSERT (lit_is_valid_utf8_string (string_p, string_size));
 
     lit_utf8_byte_t *data_p;
 
diff --git a/jerry-core/ecma/builtin-objects/ecma-builtin-global.c b/jerry-core/ecma/builtin-objects/ecma-builtin-global.c
index 58ae632a99..adba8936f5 100644
--- a/jerry-core/ecma/builtin-objects/ecma-builtin-global.c
+++ b/jerry-core/ecma/builtin-objects/ecma-builtin-global.c
@@ -899,7 +899,7 @@ ecma_builtin_global_object_decode_uri_helper (ecma_value_t uri, /**< uri argumen
         }
 
         if (!is_valid
-            || !lit_is_utf8_string_valid (octets, bytes_count))
+            || !lit_is_valid_utf8_string (octets, bytes_count))
         {
           ret_value = ecma_raise_uri_error (ECMA_ERR_MSG ("Invalid UTF8 string."));
           break;
@@ -923,7 +923,7 @@ ecma_builtin_global_object_decode_uri_helper (ecma_value_t uri, /**< uri argumen
     {
       JERRY_ASSERT (output_start_p + output_size == output_char_p);
 
-      if (lit_is_cesu8_string_valid (output_start_p, output_size))
+      if (lit_is_valid_cesu8_string (output_start_p, output_size))
       {
         ecma_string_t *output_string_p = ecma_new_ecma_string_from_utf8 (output_start_p, output_size);
         ret_value = ecma_make_string_value (output_string_p);
diff --git a/jerry-core/jerry.c b/jerry-core/jerry.c
index 2f51612c91..8ae75382db 100644
--- a/jerry-core/jerry.c
+++ b/jerry-core/jerry.c
@@ -982,7 +982,7 @@ jerry_create_object (void)
 } /* jerry_create_object */
 
 /**
- * Create string from a valid UTF8 string
+ * Create string from a valid UTF-8 string
  *
  * Note:
  *      returned value must be freed with jerry_release_value when it is no longer needed.
@@ -996,7 +996,7 @@ jerry_create_string_from_utf8 (const jerry_char_t *str_p) /**< pointer to string
 } /* jerry_create_string_from_utf8 */
 
 /**
- * Create string from a valid UTF8 string
+ * Create string from a valid UTF-8 string
  *
  * Note:
  *      returned value must be freed with jerry_release_value when it is no longer needed.
@@ -1016,7 +1016,7 @@ jerry_create_string_sz_from_utf8 (const jerry_char_t *str_p, /**< pointer to str
 } /* jerry_create_string_sz_from_utf8 */
 
 /**
- * Create string from a valid CESU8 string
+ * Create string from a valid CESU-8 string
  *
  * Note:
  *      returned value must be freed with jerry_release_value, when it is no longer needed.
@@ -1030,7 +1030,7 @@ jerry_create_string (const jerry_char_t *str_p) /**< pointer to string */
 } /* jerry_create_string */
 
 /**
- * Create string from a valid CESU8 string
+ * Create string from a valid CESU-8 string
  *
  * Note:
  *      returned value must be freed with jerry_release_value when it is no longer needed.
@@ -2006,6 +2006,34 @@ jerry_foreach_object_property (const jerry_value_t obj_val, /**< object value */
   return false;
 } /* jerry_foreach_object_property */
 
+/**
+ * Validate UTF-8 string
+ *
+ * @return true - if UTF-8 string is well-formed
+ *         false - otherwise
+ */
+bool
+jerry_is_valid_utf8_string (const jerry_char_t *utf8_buf_p, /**< UTF-8 string */
+                            jerry_size_t buf_size) /**< string size */
+{
+  return lit_is_valid_utf8_string ((lit_utf8_byte_t *) utf8_buf_p,
+                                   (lit_utf8_size_t) buf_size);
+} /* jerry_is_valid_utf8_string */
+
+/**
+ * Validate CESU-8 string
+ *
+ * @return true - if CESU-8 string is well-formed
+ *         false - otherwise
+ */
+bool
+jerry_is_valid_cesu8_string (const jerry_char_t *cesu8_buf_p, /**< CESU-8 string */
+                             jerry_size_t buf_size) /**< string size */
+{
+  return lit_is_valid_cesu8_string ((lit_utf8_byte_t *) cesu8_buf_p,
+                                    (lit_utf8_size_t) buf_size);
+} /* jerry_is_valid_cesu8_string */
+
 /**
  * @}
  */
diff --git a/jerry-core/jerryscript.h b/jerry-core/jerryscript.h
index 4a43d1444e..b2688b7619 100644
--- a/jerry-core/jerryscript.h
+++ b/jerry-core/jerryscript.h
@@ -329,6 +329,12 @@ void jerry_set_object_native_handle (const jerry_value_t obj_val, uintptr_t hand
 bool jerry_foreach_object_property (const jerry_value_t obj_val, jerry_object_property_foreach_t foreach_p,
                                     void *user_data_p);
 
+/**
+ * Input validator functions
+ */
+bool jerry_is_valid_utf8_string (const jerry_char_t *utf8_buf_p, jerry_size_t buf_size);
+bool jerry_is_valid_cesu8_string (const jerry_char_t *cesu8_buf_p, jerry_size_t buf_size);
+
 /**
  * Snapshot functions
  */
diff --git a/jerry-core/lit/lit-strings.c b/jerry-core/lit/lit-strings.c
index 277286b7c4..b633df13ce 100644
--- a/jerry-core/lit/lit-strings.c
+++ b/jerry-core/lit/lit-strings.c
@@ -28,7 +28,7 @@
  *         false otherwise
  */
 bool
-lit_is_utf8_string_valid (const lit_utf8_byte_t *utf8_buf_p, /**< utf-8 string */
+lit_is_valid_utf8_string (const lit_utf8_byte_t *utf8_buf_p, /**< utf-8 string */
                           lit_utf8_size_t buf_size) /**< string size */
 {
   lit_utf8_size_t idx = 0;
@@ -116,7 +116,7 @@ lit_is_utf8_string_valid (const lit_utf8_byte_t *utf8_buf_p, /**< utf-8 string *
   }
 
   return true;
-} /* lit_is_utf8_string_valid */
+} /* lit_is_valid_utf8_string */
 
 /**
  * Validate cesu-8 string
@@ -125,14 +125,14 @@ lit_is_utf8_string_valid (const lit_utf8_byte_t *utf8_buf_p, /**< utf-8 string *
  *         false otherwise
  */
 bool
-lit_is_cesu8_string_valid (const lit_utf8_byte_t *utf8_buf_p, /**< utf-8 string */
+lit_is_valid_cesu8_string (const lit_utf8_byte_t *cesu8_buf_p, /**< cesu-8 string */
                            lit_utf8_size_t buf_size) /**< string size */
 {
   lit_utf8_size_t idx = 0;
 
   while (idx < buf_size)
   {
-    lit_utf8_byte_t c = utf8_buf_p[idx++];
+    lit_utf8_byte_t c = cesu8_buf_p[idx++];
     if ((c & LIT_UTF8_1_BYTE_MASK) == LIT_UTF8_1_BYTE_MARKER)
     {
       continue;
@@ -166,7 +166,7 @@ lit_is_cesu8_string_valid (const lit_utf8_byte_t *utf8_buf_p, /**< utf-8 string
 
     for (lit_utf8_size_t offset = 0; offset < extra_bytes_count; ++offset)
     {
-      c = utf8_buf_p[idx + offset];
+      c = cesu8_buf_p[idx + offset];
       if ((c & LIT_UTF8_EXTRA_BYTE_MASK) != LIT_UTF8_EXTRA_BYTE_MARKER)
       {
         /* invalid continuation byte */
@@ -186,7 +186,7 @@ lit_is_cesu8_string_valid (const lit_utf8_byte_t *utf8_buf_p, /**< utf-8 string
   }
 
   return true;
-} /* lit_is_cesu8_string_valid */
+} /* lit_is_valid_cesu8_string */
 
 /**
  * Check if the code point is UTF-16 low surrogate
diff --git a/jerry-core/lit/lit-strings.h b/jerry-core/lit/lit-strings.h
index 90f82de420..c83bf82c3b 100644
--- a/jerry-core/lit/lit-strings.h
+++ b/jerry-core/lit/lit-strings.h
@@ -85,8 +85,8 @@
 #define LIT_UTF8_FIRST_BYTE_MAX LIT_UTF8_5_BYTE_MARKER
 
 /* validation */
-bool lit_is_utf8_string_valid (const lit_utf8_byte_t *utf8_buf_p, lit_utf8_size_t buf_size);
-bool lit_is_cesu8_string_valid (const lit_utf8_byte_t *utf8_buf_p, lit_utf8_size_t buf_size);
+bool lit_is_valid_utf8_string (const lit_utf8_byte_t *utf8_buf_p, lit_utf8_size_t buf_size);
+bool lit_is_valid_cesu8_string (const lit_utf8_byte_t *cesu8_buf_p, lit_utf8_size_t buf_size);
 
 /* checks */
 bool lit_is_code_point_utf16_low_surrogate (lit_code_point_t code_point);
diff --git a/jerry-main/main-unix.c b/jerry-main/main-unix.c
index ac7b13dfbe..a893342e22 100644
--- a/jerry-main/main-unix.c
+++ b/jerry-main/main-unix.c
@@ -663,6 +663,12 @@ main (int argc,
         break;
       }
 
+      if (!jerry_is_valid_utf8_string (source_p, (jerry_size_t) source_size))
+      {
+        ret_value = jerry_create_error (JERRY_ERROR_COMMON, (jerry_char_t *) ("Input must be a valid UTF-8 string."));
+        break;
+      }
+
       if (jerry_is_feature_enabled (JERRY_FEATURE_SNAPSHOT_SAVE) && (is_save_snapshot_mode || is_save_literals_mode))
       {
         static uint8_t snapshot_save_buffer[ JERRY_BUFFER_SIZE ];
@@ -686,6 +692,7 @@ main (int argc,
             fclose (snapshot_file_p);
           }
         }
+
         if (!jerry_value_has_error_flag (ret_value) && is_save_literals_mode)
         {
           const size_t literal_buffer_size = jerry_parse_and_save_literals ((jerry_char_t *) source_p,
diff --git a/tests/jerry/fail/1/regression-test-issue-1549.js b/tests/jerry/fail/1/regression-test-issue-1549.js
new file mode 100644
index 0000000000..6e2e99b72a
--- /dev/null
+++ b/tests/jerry/fail/1/regression-test-issue-1549.js
@@ -0,0 +1,15 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+va'�c=
diff --git a/tests/unit/test-strings.c b/tests/unit/test-strings.c
index 4ff6df8688..5cad4da577 100644
--- a/tests/unit/test-strings.c
+++ b/tests/unit/test-strings.c
@@ -87,7 +87,7 @@ generate_cesu8_string (lit_utf8_byte_t *buf_p,
 
     lit_utf8_size_t bytes_generated = generate_cesu8_char (char_size, buf_p);
 
-    TEST_ASSERT (lit_is_cesu8_string_valid (buf_p, bytes_generated));
+    TEST_ASSERT (lit_is_valid_cesu8_string (buf_p, bytes_generated));
 
     size += bytes_generated;
     buf_p += bytes_generated;
@@ -183,19 +183,19 @@ main ()
 
   /* Overlong-encoded code point */
   lit_utf8_byte_t invalid_cesu8_string_1[] = {0xC0, 0x82};
-  TEST_ASSERT (!lit_is_cesu8_string_valid (invalid_cesu8_string_1, sizeof (invalid_cesu8_string_1)));
+  TEST_ASSERT (!lit_is_valid_cesu8_string (invalid_cesu8_string_1, sizeof (invalid_cesu8_string_1)));
 
   /* Overlong-encoded code point */
   lit_utf8_byte_t invalid_cesu8_string_2[] = {0xE0, 0x80, 0x81};
-  TEST_ASSERT (!lit_is_cesu8_string_valid (invalid_cesu8_string_2, sizeof (invalid_cesu8_string_2)));
+  TEST_ASSERT (!lit_is_valid_cesu8_string (invalid_cesu8_string_2, sizeof (invalid_cesu8_string_2)));
 
   /* Pair of surrogates: 0xD901 0xDFF0 which encode Unicode character 0x507F0 */
   lit_utf8_byte_t invalid_cesu8_string_3[] = {0xED, 0xA4, 0x81, 0xED, 0xBF, 0xB0};
-  TEST_ASSERT (lit_is_cesu8_string_valid (invalid_cesu8_string_3, sizeof (invalid_cesu8_string_3)));
+  TEST_ASSERT (lit_is_valid_cesu8_string (invalid_cesu8_string_3, sizeof (invalid_cesu8_string_3)));
 
   /* Isolated high surrogate 0xD901 */
   lit_utf8_byte_t valid_utf8_string_1[] = {0xED, 0xA4, 0x81};
-  TEST_ASSERT (lit_is_cesu8_string_valid (valid_utf8_string_1, sizeof (valid_utf8_string_1)));
+  TEST_ASSERT (lit_is_valid_cesu8_string (valid_utf8_string_1, sizeof (valid_utf8_string_1)));
 
   lit_utf8_byte_t res_buf[3];
   lit_utf8_size_t res_size;