diff --git a/include/xo/reader/define_xs.hpp b/include/xo/reader/define_xs.hpp
index 34670230..8c9ef9c1 100644
--- a/include/xo/reader/define_xs.hpp
+++ b/include/xo/reader/define_xs.hpp
@@ -42,15 +42,12 @@ namespace xo {
 
             defexprstatetype defxs_type() const { return defxs_type_; }
 
-#ifdef OBSOLETE
-            bool admits_leftparen() const;
-#endif
+            bool admits_rightparen() const;
 
             virtual bool admits_symbol() const override;
             virtual bool admits_colon() const override;
             virtual bool admits_semicolon() const override;
             virtual bool admits_singleassign() const override;
-            virtual bool admits_rightparen() const override;
 
             // virtual void on_f64(..) override
             virtual void on_expr(ref::brw<Expression> expr,
@@ -69,11 +66,6 @@ namespace xo {
                                             rp<Expression> * /*p_emit_expr*/) override;
             virtual void on_singleassign_token(const token_type & tk,
                                                exprstatestack * p_stack) override;
-#ifdef OBSOLETE
-            virtual void on_leftparen_token(const token_type & tk,
-                                            exprstatestack * p_stack,
-                                            rp<Expression> * /*p_emit_expr*/) override;
-#endif
             virtual void on_rightparen_token(const token_type & tk,
                                              exprstatestack * p_stack,
                                              rp<Expression> * /*p_emit_expr*/) override;
diff --git a/include/xo/reader/exprstate.hpp b/include/xo/reader/exprstate.hpp
index 28ba4694..61ba3319 100644
--- a/include/xo/reader/exprstate.hpp
+++ b/include/xo/reader/exprstate.hpp
@@ -90,9 +90,9 @@ namespace xo {
 #ifdef OBSOLETE
             /** true iff this parsing state admits a leftparen '(' as next token **/
             virtual bool admits_leftparen() const;
-#endif
             /** truee iff this parsing state admits a rightparen ')' as next token **/
             virtual bool admits_rightparen() const;
+#endif
 
             /** update exprstate in response to incoming token @p tk,
              *  forward instructions to parent parser
diff --git a/include/xo/reader/paren_xs.hpp b/include/xo/reader/paren_xs.hpp
index 22b72f8b..d00dc384 100644
--- a/include/xo/reader/paren_xs.hpp
+++ b/include/xo/reader/paren_xs.hpp
@@ -32,6 +32,7 @@ namespace xo {
             static std::unique_ptr<paren_xs> lparen_0();
 
             bool admits_f64() const;
+            bool admits_rightparen() const;
 
             virtual bool admits_symbol() const override;
             virtual bool admits_colon() const override;
@@ -40,7 +41,6 @@ namespace xo {
 #ifdef OBSOLETE
             virtual bool admits_leftparen() const override;
 #endif
-            virtual bool admits_rightparen() const override;
 
             virtual void on_expr(ref::brw<Expression> expr,
                                  exprstatestack * p_stack,
diff --git a/include/xo/reader/progress_xs.hpp b/include/xo/reader/progress_xs.hpp
index 83a2ce65..d4a0c190 100644
--- a/include/xo/reader/progress_xs.hpp
+++ b/include/xo/reader/progress_xs.hpp
@@ -30,8 +30,8 @@ namespace xo {
             virtual bool admits_singleassign() const override;
 #ifdef OBSOLETE
             virtual bool admits_leftparen() const override;
-#endif
             virtual bool admits_rightparen() const override;
+#endif
 
             virtual void on_expr(ref::brw<Expression> expr,
                                  exprstatestack * p_stack,
diff --git a/src/reader/exprstate.cpp b/src/reader/exprstate.cpp
index 1fd4d08a..31553c1c 100644
--- a/src/reader/exprstate.cpp
+++ b/src/reader/exprstate.cpp
@@ -180,50 +180,6 @@ namespace xo {
         }
 
 #ifdef OBSOLETE
-        bool
-        exprstate::admits_leftparen() const {
-            switch (exs_type_) {
-            case exprstatetype::expect_toplevel_expression_sequence:
-                /* input like
-                 *   (function(blah...))
-                 * not allowed at toplevel;
-                 * creates ambiguity e.g. consider
-                 *   x := foo
-                 *   (bar)
-                 *
-                 * is rhs 'foo' or 'foo(bar)'
-                 */
-                return false;
-
-            case exprstatetype::defexpr:
-            case exprstatetype::parenexpr:
-            case exprstatetype::expect_rhs_expression:
-                /* unreachable - redirects to define_xs etc */
-                assert(false);
-                return false;
-
-            case exprstatetype::expect_type:
-                return false;
-
-            case exprstatetype::expect_symbol:
-                return false;
-
-            case exprstatetype::expr_progress:
-                /* unreachable */
-                assert(false);
-                return false;
-
-            case exprstatetype::invalid:
-            case exprstatetype::n_exprstatetype:
-                /* unreachable */
-                assert(false);
-                return false;
-            }
-
-            return false;
-        }
-#endif
-
         bool
         exprstate::admits_rightparen() const {
             switch (exs_type_) {
@@ -255,6 +211,7 @@ namespace xo {
 
             return false;
         }
+#endif
 
         void
         exprstate::on_def_token(const token_type & tk,
@@ -428,7 +385,7 @@ namespace xo {
             constexpr bool c_debug_flag = true;
             scope log(XO_DEBUG(c_debug_flag));
 
-            constexpr const char * self_name = "exprstate::on_singleassign";
+            constexpr const char * self_name = "exprstate::on_singleassign_token";
 
             if (!this->admits_singleassign())
             {
@@ -448,13 +405,13 @@ namespace xo {
             constexpr bool c_debug_flag = true;
             scope log(XO_DEBUG(c_debug_flag));
 
-            constexpr const char * self_name = "exprstate::on_leftparen";
+            constexpr const char * self_name = "exprstate::on_leftparen_token";
 
             this->illegal_input_error(self_name, tk);
         }
 
         void
-        exprstate::on_rightparen_token(const token_type & /*tk*/,
+        exprstate::on_rightparen_token(const token_type & tk,
                                        exprstatestack * /*p_stack*/,
                                        rp<Expression> * /*p_emit_expr*/)
         {
@@ -463,18 +420,7 @@ namespace xo {
 
             constexpr const char * self_name = "exprstate::on_rightparen";
 
-            if (!this->admits_rightparen())
-            {
-                throw std::runtime_error(tostr(self_name,
-                                               ": unexpected rightparen ')' for parsing state",
-                                               xtag("state", *this)));
-            }
-
-            if (this->exs_type_ == exprstatetype::expr_progress
-                || this->exs_type_ == exprstatetype::parenexpr) {
-                /* unreachable -- see progress_xs::on_rightparen() etc */
-                assert(false);
-            }
+            this->illegal_input_error(self_name, tk);
         }
 
         void
diff --git a/src/reader/progress_xs.cpp b/src/reader/progress_xs.cpp
index f5ba36ee..f518374a 100644
--- a/src/reader/progress_xs.cpp
+++ b/src/reader/progress_xs.cpp
@@ -26,11 +26,13 @@ namespace xo {
         bool
         progress_xs::admits_singleassign() const { return false; }
 
+#ifdef OBSOLETE
         bool
         progress_xs::admits_rightparen() const {
             /* satisfies expression form */
             return true;
         }
+#endif
 
         bool
         progress_xs::admits_f64() const { return false; }