diff --git a/jerry-core/lit/lit-unicode-ranges.inc.h b/jerry-core/lit/lit-unicode-ranges.inc.h
index 1749feaf6..d066a612a 100644
--- a/jerry-core/lit/lit-unicode-ranges.inc.h
+++ b/jerry-core/lit/lit-unicode-ranges.inc.h
@@ -171,11 +171,11 @@ static const uint16_t lit_unicode_non_letter_ident_part_interval_sps[] JERRY_ATT
   0x17e0, 0x180b, 0x1810, 0x1885, 0x1920, 0x1930, 0x1946, 0x19d0, 0x1a17, 0x1a55,
   0x1a60, 0x1a7f, 0x1a90, 0x1ab0, 0x1b00, 0x1b34, 0x1b50, 0x1b6b, 0x1b80, 0x1ba1,
   0x1bb0, 0x1be6, 0x1c24, 0x1c40, 0x1c50, 0x1cd0, 0x1cd4, 0x1cf2, 0x1cf8, 0x1dc0,
-  0x1dfb, 0x203f, 0x20d0, 0x20e5, 0x2cef, 0x2de0, 0x302a, 0x3099, 0xa620, 0xa674,
-  0xa69e, 0xa6f0, 0xa823, 0xa880, 0xa8b4, 0xa8d0, 0xa8e0, 0xa900, 0xa926, 0xa947,
-  0xa980, 0xa9b3, 0xa9d0, 0xa9f0, 0xaa29, 0xaa4c, 0xaa50, 0xaa7b, 0xaab2, 0xaab7,
-  0xaabe, 0xaaeb, 0xaaf5, 0xabe3, 0xabec, 0xabf0, 0xfe00, 0xfe20, 0xfe33, 0xfe4d,
-  0xff10
+  0x1dfb, 0x200c, 0x203f, 0x20d0, 0x20e5, 0x2cef, 0x2de0, 0x302a, 0x3099, 0xa620,
+  0xa674, 0xa69e, 0xa6f0, 0xa823, 0xa880, 0xa8b4, 0xa8d0, 0xa8e0, 0xa900, 0xa926,
+  0xa947, 0xa980, 0xa9b3, 0xa9d0, 0xa9f0, 0xaa29, 0xaa4c, 0xaa50, 0xaa7b, 0xaab2,
+  0xaab7, 0xaabe, 0xaaeb, 0xaaf5, 0xabe3, 0xabec, 0xabf0, 0xfe00, 0xfe20, 0xfe33,
+  0xfe4d, 0xff10
 };
 
 /**
@@ -201,11 +201,11 @@ static const uint8_t lit_unicode_non_letter_ident_part_interval_lengths[] JERRY_
   0x0009, 0x0002, 0x0009, 0x0001, 0x000b, 0x000b, 0x0009, 0x0009, 0x0004, 0x0009,
   0x001c, 0x000a, 0x0009, 0x000d, 0x0004, 0x0010, 0x0009, 0x0008, 0x0002, 0x000c,
   0x0009, 0x000d, 0x0013, 0x0009, 0x0009, 0x0002, 0x0014, 0x0002, 0x0001, 0x0035,
-  0x0004, 0x0001, 0x000c, 0x000b, 0x0002, 0x001f, 0x0005, 0x0001, 0x0009, 0x0009,
-  0x0001, 0x0001, 0x0004, 0x0001, 0x0011, 0x0009, 0x0011, 0x0009, 0x0007, 0x000c,
-  0x0003, 0x000d, 0x0009, 0x0009, 0x000d, 0x0001, 0x0009, 0x0002, 0x0002, 0x0001,
-  0x0001, 0x0004, 0x0001, 0x0007, 0x0001, 0x0009, 0x000f, 0x000f, 0x0001, 0x0002,
-  0x0009
+  0x0004, 0x0001, 0x0001, 0x000c, 0x000b, 0x0002, 0x001f, 0x0005, 0x0001, 0x0009,
+  0x0009, 0x0001, 0x0001, 0x0004, 0x0001, 0x0011, 0x0009, 0x0011, 0x0009, 0x0007,
+  0x000c, 0x0003, 0x000d, 0x0009, 0x0009, 0x000d, 0x0001, 0x0009, 0x0002, 0x0002,
+  0x0001, 0x0001, 0x0004, 0x0001, 0x0007, 0x0001, 0x0009, 0x000f, 0x000f, 0x0001,
+  0x0002, 0x0009
 };
 
 /**
diff --git a/tests/jerry/unicode-format-control-characters.js b/tests/jerry/unicode-format-control-characters.js
new file mode 100644
index 000000000..608430e2b
--- /dev/null
+++ b/tests/jerry/unicode-format-control-characters.js
@@ -0,0 +1,31 @@
+// 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.
+
+function checkSyntax (str) {
+  try {
+    eval (str);
+    assert (false);
+  } catch (e) {
+    assert (e instanceof SyntaxError);
+  }
+}
+
+// Only \u200C-Zero width non-joiner, and \u200D-Zero width joiner are allowed
+
+checkSyntax ("_\u200b\u200d");
+checkSyntax ("_\u200c\u200e");
+
+var _\u200c\u200d = 5;
+
+assert (_\u200c\u200d === 5);
diff --git a/tools/gen-unicode.py b/tools/gen-unicode.py
index 34f8ace96..b70735822 100755
--- a/tools/gen-unicode.py
+++ b/tools/gen-unicode.py
@@ -137,6 +137,14 @@ class UnicodeCategorizer(object):
         if zero_width_space not in separators:
             bisect.insort(separators, int(zero_width_space))
 
+        # https://www.ecma-international.org/ecma-262/5.1/#sec-7.1 format-control characters
+        non_letters = self._categories['non_letters']
+        zero_width_non_joiner = 0x200C
+        zero_width_joiner = 0x200D
+
+        bisect.insort(non_letters, int(zero_width_non_joiner))
+        bisect.insort(non_letters, int(zero_width_joiner))
+
         return self._categories['letters'], self._categories['non_letters'], self._categories['separators']