diff --git a/src/compiler/prepare_grammar/parse_regex.cc b/src/compiler/prepare_grammar/parse_regex.cc
index 8ab84fb2..2b386907 100644
--- a/src/compiler/prepare_grammar/parse_regex.cc
+++ b/src/compiler/prepare_grammar/parse_regex.cc
@@ -121,7 +121,7 @@ class PatternParser {
                 vector<Rule> optional_entries(max_count - min_count, Rule::choice({result, Blank{}}));
                 entries.insert(entries.end(), optional_entries.begin(), optional_entries.end());
               } else if (has_comma) {
-                entries.push_back(Rule::repeat(result));
+                entries.push_back(Rule::choice({Rule::repeat(result), Blank{} }));
               }
               result = Rule::seq(entries);
             } else if (max_repeat_string.size()) {
diff --git a/test/compiler/prepare_grammar/parse_regex_test.cc b/test/compiler/prepare_grammar/parse_regex_test.cc
index fe189975..27fd43b1 100644
--- a/test/compiler/prepare_grammar/parse_regex_test.cc
+++ b/test/compiler/prepare_grammar/parse_regex_test.cc
@@ -305,7 +305,10 @@ describe("parse_regex", []() {
         CharacterSet{{' '}},
         Rule::seq({
           CharacterSet{{'b'}},
-          Repeat{CharacterSet{{'b'}}},
+          Rule::choice({
+            Repeat{CharacterSet{{'b'}}},
+            Blank{}
+          }),
         }),
         CharacterSet{{' '}},
         Rule::seq({