diff --git a/parso/pgen2/grammar.py b/parso/pgen2/grammar.py
index c1c4aff..2d7948d 100644
--- a/parso/pgen2/grammar.py
+++ b/parso/pgen2/grammar.py
@@ -36,8 +36,8 @@ class Grammar(object):
     do this (see the conv and pgen modules).
     """
 
-    def __init__(self, bnf_grammar, start_nonterminal, rule_to_dfas, reserved_syntax_strings):
-        self._nonterminal_to_dfas = rule_to_dfas
+    def __init__(self, start_nonterminal, rule_to_dfas, reserved_syntax_strings):
+        self.nonterminal_to_dfas = rule_to_dfas
 
         self.reserved_syntax_strings = reserved_syntax_strings
         self.start_nonterminal = start_nonterminal
@@ -48,7 +48,7 @@ class Grammar(object):
         # Map from grammar rule (nonterminal) name to a set of tokens.
         self._first_plans = {}
 
-        nonterminals = list(self._nonterminal_to_dfas.keys())
+        nonterminals = list(self.nonterminal_to_dfas.keys())
         nonterminals.sort()
         for nonterminal in nonterminals:
             if nonterminal not in self._first_plans:
@@ -57,14 +57,14 @@ class Grammar(object):
         # Now that we have calculated the first terminals, we are sure that
         # there is no left recursion or ambiguities.
 
-        for dfas in self._nonterminal_to_dfas.values():
+        for dfas in self.nonterminal_to_dfas.values():
             for dfa_state in dfas:
                 for nonterminal, next_dfa in dfa_state.nonterminal_arcs.items():
                     for transition, pushes in self._first_plans[nonterminal].items():
                         dfa_state.ilabel_to_plan[transition] = DFAPlan(next_dfa, pushes)
 
     def _calculate_first_terminals(self, nonterminal):
-        dfas = self._nonterminal_to_dfas[nonterminal]
+        dfas = self.nonterminal_to_dfas[nonterminal]
         new_first_plans = {}
         self._first_plans[nonterminal] = None  # dummy to detect left recursion
         # We only need to check the first dfa. All the following ones are not
diff --git a/parso/pgen2/parse.py b/parso/pgen2/parse.py
index 646eb58..3965d2d 100644
--- a/parso/pgen2/parse.py
+++ b/parso/pgen2/parse.py
@@ -138,7 +138,7 @@ class PgenParser(object):
         self.convert_node = convert_node
         self.convert_leaf = convert_leaf
 
-        self.stack = Stack([StackNode(grammar._nonterminal_to_dfas[start_nonterminal][0])])
+        self.stack = Stack([StackNode(grammar.nonterminal_to_dfas[start_nonterminal][0])])
         self.error_recovery = error_recovery
 
     def parse(self, tokens):
diff --git a/parso/pgen2/pgen.py b/parso/pgen2/pgen.py
index 3dd9f2a..d211941 100644
--- a/parso/pgen2/pgen.py
+++ b/parso/pgen2/pgen.py
@@ -209,7 +209,7 @@ def generate_grammar(bnf_grammar, token_namespace):
                     )
                     dfa_state.ilabel_to_plan[transition] = DFAPlan(next_dfa)
 
-    return Grammar(bnf_grammar, start_nonterminal, rule_to_dfas, reserved_strings)
+    return Grammar(start_nonterminal, rule_to_dfas, reserved_strings)
 
 
 def _make_transition(token_namespace, reserved_syntax_strings, label):