diff --git a/include/xo/reader/expect_formal_arglist_xs.hpp b/include/xo/reader/expect_formal_arglist_xs.hpp
index 5bf75a8f..f3a6bf22 100644
--- a/include/xo/reader/expect_formal_arglist_xs.hpp
+++ b/include/xo/reader/expect_formal_arglist_xs.hpp
@@ -53,7 +53,7 @@ namespace xo {
         public:
             expect_formal_arglist_xs();
 
-            static void start(exprstatestack * p_stack);
+            static void start(parserstatemachine * p_psm);
 
             virtual void on_leftparen_token(const token_type & tk,
                                             parserstatemachine * p_psm) override;
diff --git a/src/reader/expect_formal_arglist_xs.cpp b/src/reader/expect_formal_arglist_xs.cpp
index 8e455413..916841da 100644
--- a/src/reader/expect_formal_arglist_xs.cpp
+++ b/src/reader/expect_formal_arglist_xs.cpp
@@ -38,9 +38,9 @@ namespace xo {
         }
 
         void
-        expect_formal_arglist_xs::start(exprstatestack * p_stack)
+        expect_formal_arglist_xs::start(parserstatemachine * p_psm)
         {
-            p_stack->push_exprstate(expect_formal_arglist_xs::make());
+            p_psm->push_exprstate(expect_formal_arglist_xs::make());
         }
 
         expect_formal_arglist_xs::expect_formal_arglist_xs()
diff --git a/src/reader/lambda_xs.cpp b/src/reader/lambda_xs.cpp
index 491ab908..8fd2f46f 100644
--- a/src/reader/lambda_xs.cpp
+++ b/src/reader/lambda_xs.cpp
@@ -30,11 +30,9 @@ namespace xo {
         lambda_xs::on_lambda_token(const token_type & tk,
                                    parserstatemachine * p_psm)
         {
-            auto p_stack = p_psm->p_stack_;
-
             if (lmxs_type_ == lambdastatetype::lm_0) {
                 this->lmxs_type_ = lambdastatetype::lm_1;
-                expect_formal_arglist_xs::start(p_stack);
+                expect_formal_arglist_xs::start(p_psm);
             } else {
                 exprstate::on_lambda_token(tk, p_psm);
             }