diff --git a/jerry-core/lit/lit-strings.c b/jerry-core/lit/lit-strings.c
index 3ac97feca..edc75f8a2 100644
--- a/jerry-core/lit/lit-strings.c
+++ b/jerry-core/lit/lit-strings.c
@@ -865,7 +865,7 @@ lit_convert_cesu8_string_to_utf8_string (const lit_utf8_byte_t *cesu8_string_p,
     cesu8_cursor_p += read_size;
   }
 
-  JERRY_ASSERT (cesu8_cursor_p == cesu8_end_p);
+  JERRY_ASSERT (cesu8_cursor_p <= cesu8_end_p);
   JERRY_ASSERT (utf8_cursor_p <= utf8_end_p);
 
   return (lit_utf8_byte_t) (utf8_cursor_p - utf8_string_p);
diff --git a/tests/jerry/fail/regression-test-issue-4920.js b/tests/jerry/fail/regression-test-issue-4920.js
new file mode 100644
index 000000000..e9138bbf9
--- /dev/null
+++ b/tests/jerry/fail/regression-test-issue-4920.js
@@ -0,0 +1,17 @@
+// 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.
+
+const v2 = String.fromCodePoint(1337);
+const v4 = v2.padEnd(1337, v2);
+const v7 = undefined[v4];