diff --git a/parso/pgen2/generator.py b/parso/pgen2/generator.py
index e64577e..d5355d3 100644
--- a/parso/pgen2/generator.py
+++ b/parso/pgen2/generator.py
@@ -282,6 +282,10 @@ def _calculate_first_plans(nonterminal_to_dfas, first_plans, nonterminal):
     # We only need to check the first dfa. All the following ones are not
     # interesting to find first terminals.
     state = dfas[0]
+    for transition, next_ in state.ilabel_to_plan.items():
+        # It's a string. We have finally found a possible first token.
+        new_first_plans[transition] = [next_.next_dfa]
+
     for nonterminal2, next_ in state.nonterminal_arcs.items():
         # It's a nonterminal and we have either a left recursion issue
         # in the grammar or we have to recurse.
@@ -303,9 +307,5 @@ def _calculate_first_plans(nonterminal_to_dfas, first_plans, nonterminal):
                 )
             new_first_plans[t] = [next_] + pushes
 
-    for transition, next_ in state.ilabel_to_plan.items():
-        # It's a string. We have finally found a possible first token.
-        new_first_plans[transition] = [next_.next_dfa]
-
     first_plans[nonterminal] = new_first_plans
     return new_first_plans
diff --git a/test/test_pgen2.py b/test/test_pgen2.py
index 6ea96a4..fe22d5b 100644
--- a/test/test_pgen2.py
+++ b/test/test_pgen2.py
@@ -285,3 +285,6 @@ def test_ambiguities():
 
     with pytest.raises(ValueError, match='ambiguous'):
         generate_grammar('''foo: bar | baz\nbar: 'x'\nbaz: "x"\n''', tokenize.PythonTokenTypes)
+
+    with pytest.raises(ValueError, match='ambiguous'):
+        generate_grammar('''foo: bar | 'x'\nbar: 'x'\n''', tokenize.PythonTokenTypes)