diff --git a/hy/_compat.py b/hy/_compat.py
index cbe0fad..518434c 100644
--- a/hy/_compat.py
+++ b/hy/_compat.py
@@ -9,10 +9,6 @@ PY36 = sys.version_info >= (3, 6)
 PY37 = sys.version_info >= (3, 7)
 PY38 = sys.version_info >= (3, 8)
 
-# The value of UCS4 indicates whether Unicode strings are stored as UCS-4.
-# It is always true on Pythons >= 3.3, which use USC-4 on all systems.
-UCS4 = sys.maxunicode == 0x10FFFF
-
 
 def reraise(exc_type, value, traceback=None):
     try:
diff --git a/hy/lex/__init__.py b/hy/lex/__init__.py
index b29709c..e2e5a26 100644
--- a/hy/lex/__init__.py
+++ b/hy/lex/__init__.py
@@ -8,7 +8,7 @@ import re
 import sys
 import unicodedata
 
-from hy._compat import isidentifier, UCS4
+from hy._compat import isidentifier
 from hy.lex.exceptions import PrematureEndOfInput, LexException  # NOQA
 from hy.models import HyExpression, HySymbol
 
@@ -135,7 +135,7 @@ def mangle(s):
                else '{0}{1}{0}'.format(mangle_delim,
                    unicodedata.name(c, '').lower().replace('-', 'H').replace(' ', '_')
                    or 'U{}'.format(unicode_char_to_hex(c)))
-            for c in unicode_to_ucs4iter(s))
+            for c in s)
 
     s = leading_underscores + s
     assert isidentifier(s)
@@ -168,19 +168,6 @@ def unmangle(s):
     return '-' * leading_underscores + s
 
 
-def unicode_to_ucs4iter(ustr):
-    # Covert a unicode string to an iterable object,
-    # elements in the object are single USC-4 unicode characters
-    if UCS4:
-        return ustr
-    ucs4_list = list(ustr)
-    for i, u in enumerate(ucs4_list):
-        if 0xD7FF < ord(u) < 0xDC00:
-            ucs4_list[i] += ucs4_list[i + 1]
-            del ucs4_list[i + 1]
-    return ucs4_list
-
-
 def read(from_file=sys.stdin, eof=""):
     """Read from input and returns a tokenized string.