diff --git a/jerry-core/CMakeLists.txt b/jerry-core/CMakeLists.txt
index 13688953ba..7c57bd8aea 100644
--- a/jerry-core/CMakeLists.txt
+++ b/jerry-core/CMakeLists.txt
@@ -17,23 +17,24 @@ set(JERRY_CORE_NAME jerry-core)
 project (${JERRY_CORE_NAME} C)
 
 # Optional features
-set(FEATURE_CPOINTER_32_BIT  OFF     CACHE BOOL   "Enable 32 bit compressed pointers?")
-set(FEATURE_DEBUGGER         OFF     CACHE BOOL   "Enable JerryScript debugger?")
-set(FEATURE_ERROR_MESSAGES   OFF     CACHE BOOL   "Enable error messages?")
-set(FEATURE_EXTERNAL_CONTEXT OFF     CACHE BOOL   "Enable external context?")
-set(FEATURE_JS_PARSER        ON      CACHE BOOL   "Enable js-parser?")
-set(FEATURE_MEM_STATS        OFF     CACHE BOOL   "Enable memory statistics?")
-set(FEATURE_MEM_STRESS_TEST  OFF     CACHE BOOL   "Enable mem-stress test?")
-set(FEATURE_PARSER_DUMP      OFF     CACHE BOOL   "Enable parser byte-code dumps?")
-set(FEATURE_PROFILE          "es5.1" CACHE STRING "Use default or other profile?")
-set(FEATURE_REGEXP_DUMP      OFF     CACHE BOOL   "Enable regexp byte-code dumps?")
-set(FEATURE_SNAPSHOT_EXEC    OFF     CACHE BOOL   "Enable executing snapshot files?")
-set(FEATURE_SNAPSHOT_SAVE    OFF     CACHE BOOL   "Enable saving snapshot files?")
-set(FEATURE_SYSTEM_ALLOCATOR OFF     CACHE BOOL   "Enable system allocator?")
-set(FEATURE_VALGRIND         OFF     CACHE BOOL   "Enable Valgrind support?")
-set(FEATURE_VALGRIND_FREYA   OFF     CACHE BOOL   "Enable Valgrind-Freya support?")
-set(FEATURE_VM_EXEC_STOP     OFF     CACHE BOOL   "Enable VM execution stopping?")
-set(MEM_HEAP_SIZE_KB         "512"   CACHE STRING "Size of memory heap, in kilobytes")
+set(FEATURE_CPOINTER_32_BIT    OFF     CACHE BOOL   "Enable 32 bit compressed pointers?")
+set(FEATURE_DEBUGGER           OFF     CACHE BOOL   "Enable JerryScript debugger?")
+set(FEATURE_ERROR_MESSAGES     OFF     CACHE BOOL   "Enable error messages?")
+set(FEATURE_EXTERNAL_CONTEXT   OFF     CACHE BOOL   "Enable external context?")
+set(FEATURE_JS_PARSER          ON      CACHE BOOL   "Enable js-parser?")
+set(FEATURE_MEM_STATS          OFF     CACHE BOOL   "Enable memory statistics?")
+set(FEATURE_MEM_STRESS_TEST    OFF     CACHE BOOL   "Enable mem-stress test?")
+set(FEATURE_PARSER_DUMP        OFF     CACHE BOOL   "Enable parser byte-code dumps?")
+set(FEATURE_PROFILE            "es5.1" CACHE STRING "Use default or other profile?")
+set(FEATURE_REGEXP_STRICT_MODE OFF     CACHE BOOL   "Enable regexp strict mode?")
+set(FEATURE_REGEXP_DUMP        OFF     CACHE BOOL   "Enable regexp byte-code dumps?")
+set(FEATURE_SNAPSHOT_EXEC      OFF     CACHE BOOL   "Enable executing snapshot files?")
+set(FEATURE_SNAPSHOT_SAVE      OFF     CACHE BOOL   "Enable saving snapshot files?")
+set(FEATURE_SYSTEM_ALLOCATOR   OFF     CACHE BOOL   "Enable system allocator?")
+set(FEATURE_VALGRIND           OFF     CACHE BOOL   "Enable Valgrind support?")
+set(FEATURE_VALGRIND_FREYA     OFF     CACHE BOOL   "Enable Valgrind-Freya support?")
+set(FEATURE_VM_EXEC_STOP       OFF     CACHE BOOL   "Enable VM execution stopping?")
+set(MEM_HEAP_SIZE_KB           "512"   CACHE STRING "Size of memory heap, in kilobytes")
 
 # Option overrides
 if(FEATURE_SYSTEM_ALLOCATOR)
@@ -57,23 +58,24 @@ if(JERRY_CMDLINE_SNAPSHOT)
 endif()
 
 # Status messages
-message(STATUS "FEATURE_CPOINTER_32_BIT   " ${FEATURE_CPOINTER_32_BIT} ${FEATURE_CPOINTER_32_BIT_MESSAGE})
-message(STATUS "FEATURE_DEBUGGER          " ${FEATURE_DEBUGGER})
-message(STATUS "FEATURE_ERROR_MESSAGES    " ${FEATURE_ERROR_MESSAGES})
-message(STATUS "FEATURE_EXTERNAL_CONTEXT  " ${FEATURE_EXTERNAL_CONTEXT})
-message(STATUS "FEATURE_JS_PARSER         " ${FEATURE_JS_PARSER})
-message(STATUS "FEATURE_MEM_STATS         " ${FEATURE_MEM_STATS})
-message(STATUS "FEATURE_MEM_STRESS_TEST   " ${FEATURE_MEM_STRESS_TEST})
-message(STATUS "FEATURE_PARSER_DUMP       " ${FEATURE_PARSER_DUMP} ${FEATURE_PARSER_DUMP_MESSAGE})
-message(STATUS "FEATURE_PROFILE           " ${FEATURE_PROFILE})
-message(STATUS "FEATURE_REGEXP_DUMP       " ${FEATURE_REGEXP_DUMP})
-message(STATUS "FEATURE_SNAPSHOT_EXEC     " ${FEATURE_SNAPSHOT_EXEC} ${FEATURE_SNAPSHOT_EXEC_MESSAGE})
-message(STATUS "FEATURE_SNAPSHOT_SAVE     " ${FEATURE_SNAPSHOT_SAVE} ${FEATURE_SNAPSHOT_SAVE_MESSAGE})
-message(STATUS "FEATURE_SYSTEM_ALLOCATOR  " ${FEATURE_SYSTEM_ALLOCATOR})
-message(STATUS "FEATURE_VALGRIND          " ${FEATURE_VALGRIND})
-message(STATUS "FEATURE_VALGRIND_FREYA    " ${FEATURE_VALGRIND_FREYA})
-message(STATUS "FEATURE_VM_EXEC_STOP      " ${FEATURE_VM_EXEC_STOP})
-message(STATUS "MEM_HEAP_SIZE_KB          " ${MEM_HEAP_SIZE_KB})
+message(STATUS "FEATURE_CPOINTER_32_BIT     " ${FEATURE_CPOINTER_32_BIT} ${FEATURE_CPOINTER_32_BIT_MESSAGE})
+message(STATUS "FEATURE_DEBUGGER            " ${FEATURE_DEBUGGER})
+message(STATUS "FEATURE_ERROR_MESSAGES      " ${FEATURE_ERROR_MESSAGES})
+message(STATUS "FEATURE_EXTERNAL_CONTEXT    " ${FEATURE_EXTERNAL_CONTEXT})
+message(STATUS "FEATURE_JS_PARSER           " ${FEATURE_JS_PARSER})
+message(STATUS "FEATURE_MEM_STATS           " ${FEATURE_MEM_STATS})
+message(STATUS "FEATURE_MEM_STRESS_TEST     " ${FEATURE_MEM_STRESS_TEST})
+message(STATUS "FEATURE_PARSER_DUMP         " ${FEATURE_PARSER_DUMP} ${FEATURE_PARSER_DUMP_MESSAGE})
+message(STATUS "FEATURE_PROFILE             " ${FEATURE_PROFILE})
+message(STATUS "FEATURE_REGEXP_STRICT_MODE  " ${FEATURE_REGEXP_STRICT_MODE})
+message(STATUS "FEATURE_REGEXP_DUMP         " ${FEATURE_REGEXP_DUMP})
+message(STATUS "FEATURE_SNAPSHOT_EXEC       " ${FEATURE_SNAPSHOT_EXEC} ${FEATURE_SNAPSHOT_EXEC_MESSAGE})
+message(STATUS "FEATURE_SNAPSHOT_SAVE       " ${FEATURE_SNAPSHOT_SAVE} ${FEATURE_SNAPSHOT_SAVE_MESSAGE})
+message(STATUS "FEATURE_SYSTEM_ALLOCATOR    " ${FEATURE_SYSTEM_ALLOCATOR})
+message(STATUS "FEATURE_VALGRIND            " ${FEATURE_VALGRIND})
+message(STATUS "FEATURE_VALGRIND_FREYA      " ${FEATURE_VALGRIND_FREYA})
+message(STATUS "FEATURE_VM_EXEC_STOP        " ${FEATURE_VM_EXEC_STOP})
+message(STATUS "MEM_HEAP_SIZE_KB            " ${MEM_HEAP_SIZE_KB})
 
 # Include directories
 set(INCLUDE_CORE
@@ -224,6 +226,11 @@ if(JERRY_LIBC AND FEATURE_SYSTEM_ALLOCATOR)
   MESSAGE(FATAL_ERROR "This configuration is not supported. Please build against your system libc to enable the system allocator.")
 endif()
 
+# RegExp strict mode
+if(FEATURE_REGEXP_STRICT_MODE)
+  set(DEFINES_JERRY ${DEFINES_JERRY} ENABLE_REGEXP_STRICT_MODE)
+endif()
+
 # RegExp byte-code dumps
 if(FEATURE_REGEXP_DUMP)
   set(DEFINES_JERRY ${DEFINES_JERRY} REGEXP_DUMP_BYTE_CODE)
diff --git a/jerry-core/parser/regexp/re-parser.c b/jerry-core/parser/regexp/re-parser.c
index 7479603dbd..0046acea24 100644
--- a/jerry-core/parser/regexp/re-parser.c
+++ b/jerry-core/parser/regexp/re-parser.c
@@ -881,9 +881,35 @@ re_parse_next_token (re_parser_ctx_t *parser_ctx_p, /**< RegExp parser context *
     case LIT_CHAR_QUESTION:
     case LIT_CHAR_ASTERISK:
     case LIT_CHAR_PLUS:
+    {
+      return ecma_raise_syntax_error (ECMA_ERR_MSG ("Invalid RegExp token."));
+    }
     case LIT_CHAR_LEFT_BRACE:
     {
+#ifdef ENABLE_REGEXP_STRICT_MODE
       return ecma_raise_syntax_error (ECMA_ERR_MSG ("Invalid RegExp token."));
+#else /* !ENABLE_REGEXP_STRICT_MODE */
+      const lit_utf8_byte_t *input_curr_p = parser_ctx_p->input_curr_p;
+
+      lit_utf8_decr (&parser_ctx_p->input_curr_p);
+      if (ecma_is_value_empty (re_parse_iterator (parser_ctx_p, out_token_p)))
+      {
+        return ecma_raise_syntax_error (ECMA_ERR_MSG ("Invalid RegExp token."));
+      }
+
+      parser_ctx_p->input_curr_p = input_curr_p;
+
+      out_token_p->type = RE_TOK_CHAR;
+      out_token_p->value = ch;
+      ret_value = re_parse_iterator (parser_ctx_p, out_token_p);
+
+      if (!ecma_is_value_empty (ret_value))
+      {
+        parser_ctx_p->input_curr_p = input_curr_p;
+        ret_value = ECMA_VALUE_EMPTY;
+      }
+#endif /* ENABLE_REGEXP_STRICT_MODE */
+      break;
     }
     case LIT_CHAR_NULL:
     {
diff --git a/tools/build.py b/tools/build.py
index 06b67b97f7..8030239f8a 100755
--- a/tools/build.py
+++ b/tools/build.py
@@ -126,6 +126,8 @@ def devhelp(helpstring):
                           help=devhelp('enable memory statistics (%(choices)s; default: %(default)s)'))
     devgroup.add_argument('--mem-stress-test', metavar='X', choices=['ON', 'OFF'], default='OFF', type=str.upper,
                           help=devhelp('enable mem-stress test (%(choices)s; default: %(default)s)'))
+    devgroup.add_argument('--regexp-strict-mode', metavar='X', choices=['ON', 'OFF'], default='OFF', type=str.upper,
+                          help=devhelp('enable regexp strict mode (%(choices)s; default: %(default)s)'))
     devgroup.add_argument('--show-opcodes', metavar='X', choices=['ON', 'OFF'], default='OFF', type=str.upper,
                           help=devhelp('enable parser byte-code dumps (%(choices)s; default: %(default)s)'))
     devgroup.add_argument('--show-regexp-opcodes', metavar='X', choices=['ON', 'OFF'], default='OFF', type=str.upper,
@@ -186,6 +188,7 @@ def generate_build_options(arguments):
     build_options.append('-DFEATURE_MEM_STATS=%s' % arguments.mem_stats)
     build_options.append('-DFEATURE_MEM_STRESS_TEST=%s' % arguments.mem_stress_test)
     build_options.append('-DFEATURE_PARSER_DUMP=%s' % arguments.show_opcodes)
+    build_options.append('-DFEATURE_REGEXP_STRICT_MODE=%s' % arguments.regexp_strict_mode)
     build_options.append('-DFEATURE_REGEXP_DUMP=%s' % arguments.show_regexp_opcodes)
     build_options.append('-DFEATURE_VALGRIND=%s' % arguments.valgrind)
     build_options.append('-DFEATURE_VALGRIND_FREYA=%s' % arguments.valgrind_freya)