diff --git a/tatsu/ngcodegen/python.py b/tatsu/ngcodegen/python.py
index 30725801..6a83e5c5 100644
--- a/tatsu/ngcodegen/python.py
+++ b/tatsu/ngcodegen/python.py
@@ -243,24 +243,24 @@ def walk_PositiveClosure(self, closure: grammars.PositiveClosure):
         self.print(f'self._positive_closure(block{n})')
 
     def walk_Join(self, join: grammars.Join):
-        n = self._gen_block(join.sep, name='sep')
+        m = self._gen_block(join.sep, name='sep')
         n = self._gen_block(join.exp)
-        self.print(f'self._join(block{n}, sep{n})')
+        self.print(f'self._join(block{n}, sep{m})')
 
     def walk_PositiveJoin(self, join: grammars.PositiveJoin):
-        n = self._gen_block(join.sep, name='sep')
+        m = self._gen_block(join.sep, name='sep')
         n = self._gen_block(join.exp)
-        self.print(f'self._positive_join(block{n}, sep{n})')
+        self.print(f'self._positive_join(block{n}, sep{m})')
 
     def walk_LeftJoin(self, join: grammars.LeftJoin):
-        n = self._gen_block(join.sep, name='sep')
+        m = self._gen_block(join.sep, name='sep')
         n = self._gen_block(join.exp)
-        self.print(f'self._left_join(block{n}, sep{n})')
+        self.print(f'self._left_join(block{n}, sep{m})')
 
     def walk_RightJoin(self, join: grammars.RightJoin):
-        n = self._gen_block(join.sep, name='sep')
+        m = self._gen_block(join.sep, name='sep')
         n = self._gen_block(join.exp)
-        self.print(f'self._right_join(block{n}, sep{n})')
+        self.print(f'self._right_join(block{n}, sep{m})')
 
     def walk_Gather(self, gather: grammars.Gather):
         m = self._gen_block(gather.sep, name='sep')
diff --git a/test/parser_equivalence_test.py b/test/parser_equivalence_test.py
index 27ed9c4b..02b4367f 100644
--- a/test/parser_equivalence_test.py
+++ b/test/parser_equivalence_test.py
@@ -170,3 +170,22 @@ def test_none_whitespace():
     parser = generate_and_load_parser('W', grammar)
     output = parser.parse(input, parseinfo=False)
     assert output == ('This is a', ' test')
+
+def test_sep_join():
+    grammar = """
+    @@grammar::numbers
+
+    start
+        = expression $
+        ;
+
+    expression
+        = ~ ( "," )%{ digit }+
+        ;
+
+    digit = /\d+/ ;
+    """
+    parser = generate_and_load_parser('W', grammar)
+    ast = parser.parse('1,2,3,4', nameguard=False)
+
+