diff --git a/py/lexer.c b/py/lexer.c
index 13c3a3e9b5..8a8875ed51 100644
--- a/py/lexer.c
+++ b/py/lexer.c
@@ -492,11 +492,19 @@ STATIC void mp_lexer_next_token_into(mp_lexer_t *lex, bool first_token) {
                         }
                     }
                     if (c != MP_LEXER_EOF) {
+                        #if MICROPY_PY_BUILTINS_STR_UNICODE
                         if (c < 0x110000 && !is_bytes) {
                             vstr_add_char(&lex->vstr, c);
                         } else if (c < 0x100 && is_bytes) {
                             vstr_add_byte(&lex->vstr, c);
-                        } else {
+                        }
+                        #else
+                        // without unicode everything is just added as an 8-bit byte
+                        if (c < 0x100) {
+                            vstr_add_byte(&lex->vstr, c);
+                        }
+                        #endif
+                        else {
                             assert(!"TODO: Throw an error, invalid escape code probably");
                         }
                     }
diff --git a/py/misc.h b/py/misc.h
index 42d30055f9..b9ef68badd 100644
--- a/py/misc.h
+++ b/py/misc.h
@@ -92,7 +92,15 @@ size_t m_get_peak_bytes_allocated(void);
 
 /** unichar / UTF-8 *********************************************/
 
-typedef int unichar; // TODO
+#if MICROPY_PY_BUILTINS_STR_UNICODE
+#include <stdint.h> // only include if we need it
+// with unicode enabled we need a type which can fit chars up to 0x10ffff
+typedef uint32_t unichar;
+#else
+// without unicode enabled we can only need to fit chars up to 0xff
+// (on 16-bit archs uint is 16-bits and more efficient than uint32_t)
+typedef uint unichar;
+#endif
 
 unichar utf8_get_char(const byte *s);
 const byte *utf8_next_char(const byte *s);
diff --git a/py/modbuiltins.c b/py/modbuiltins.c
index 68a22934b1..d537d49dea 100644
--- a/py/modbuiltins.c
+++ b/py/modbuiltins.c
@@ -182,11 +182,11 @@ STATIC mp_obj_t mp_builtin_chr(mp_obj_t o_in) {
     return mp_obj_new_str(str, len, true);
     #else
     mp_int_t ord = mp_obj_get_int(o_in);
-    if (0 <= ord && ord <= 0x10ffff) {
+    if (0 <= ord && ord <= 0xff) {
         char str[1] = {ord};
         return mp_obj_new_str(str, 1, true);
     } else {
-        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "chr() arg not in range(0x110000)"));
+        nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "chr() arg not in range(256)"));
     }
     #endif
 }