diff --git a/src/parser/parser.l b/src/parser/parser.l
index b046d60..723850b 100644
--- a/src/parser/parser.l
+++ b/src/parser/parser.l
@@ -137,7 +137,14 @@ L?'\\v'             (void)'\v'; return TOK_CHAR_CONST;
 \\x[0-9A-Fa-f]{2} {
                     /* hexadecimal escape code */
                     unsigned int val;
-                    (void) sscanf(yytext + 2, "%x", &val);
+                    (void)sscanf(yytext + 1, "%x", &val);
+                    char v[2] = {(char)val, '\0'};
+                    String_concat(build_string, v);
+}
+\\[0-7][0-7]?[0-7]? {
+                    /* octal escape code */
+                    unsigned int val;
+                    (void)sscanf(yytext + 1, "%o", &val);
                     char v[2] = {(char)val, '\0'};
                     String_concat(build_string, v);
 }