diff --git a/lexer.c b/lexer.c
index 065f60c..6bd47b0 100644
--- a/lexer.c
+++ b/lexer.c
@@ -1290,6 +1290,14 @@ int lex_do(lex_file *lex)
         {
              lex->tok.ttype = TOKEN_VECTORCONST;
         }
+        else
+        {
+            if (!lex->flags.preprocessing && strlen(lex->tok.value) > 1) {
+                if (lexwarn(lex, WARN_MULTIBYTE_CHARACTER, "multibyte character: `%s`", lex->tok.value))
+                    return (lex->tok.ttype = TOKEN_ERROR);
+            }
+            lex->tok.constval.i = lex->tok.value[0];
+        }
 
         return lex->tok.ttype;
     }
diff --git a/main.c b/main.c
index d35e33f..6ee7d8e 100644
--- a/main.c
+++ b/main.c
@@ -473,6 +473,8 @@ int main(int argc, char **argv) {
     options_set(opts_warn, WARN_PREPROCESSOR, true);
     options_set(opts_warn, WARN_MULTIFILE_IF, true);
     options_set(opts_warn, WARN_DOUBLE_DECLARATION, true);
+    options_set(opts_warn, WARN_CONST_VAR, true);
+    options_set(opts_warn, WARN_MULTIBYTE_CHARACTER, true);
 
     options_set(opts_flags, ADJUST_VECTOR_FIELDS, true);
     options_set(opts_flags, FTEPP, false);
diff --git a/opts.def b/opts.def
index c083c2b..7f4c15e 100644
--- a/opts.def
+++ b/opts.def
@@ -62,6 +62,7 @@
     GMQCC_DEFINE_FLAG(MULTIFILE_IF)
     GMQCC_DEFINE_FLAG(DOUBLE_DECLARATION)
     GMQCC_DEFINE_FLAG(CONST_VAR)
+    GMQCC_DEFINE_FLAG(MULTIBYTE_CHARACTER)
 #endif
 
 /* some cleanup so we don't have to */
diff --git a/parser.c b/parser.c
index e7e205d..c840ae6 100644
--- a/parser.c
+++ b/parser.c
@@ -1428,7 +1428,7 @@ static ast_expression* parse_expression_leave(parser_t *parser, bool stopatcomma
             vec_push(sy.out, syexp(parser_ctx(parser), (ast_expression*)val));
             DEBUGSHUNTDO(con_out("push %g\n", parser_token(parser)->constval.f));
         }
-        else if (parser->tok == TOKEN_INTCONST) {
+        else if (parser->tok == TOKEN_INTCONST || parser->tok == TOKEN_CHARCONST) {
             ast_value *val;
             if (wantop) {
                 parseerror(parser, "expected operator or end of statement, got constant");