diff --git a/include/xo/reader2/ParserStateMachine.hpp b/include/xo/reader2/ParserStateMachine.hpp
index f5001faa..cc313660 100644
--- a/include/xo/reader2/ParserStateMachine.hpp
+++ b/include/xo/reader2/ParserStateMachine.hpp
@@ -351,15 +351,6 @@ namespace xo {
             /** @defgroup scm-parserstatemachine-gcobject-facet gc support **/
             ///@{
 
-#ifdef OBSOLETE
-            std::size_t shallow_size() const noexcept;
-            /** NOTE:
-             *  ParserStateMachine only eligible to be a GC root.
-             *  It's not eligible to reside in gc-owned space
-             **/
-            ParserStateMachine * shallow_copy(obj<AAllocator> mm) const noexcept;
-            std::size_t forward_children(obj<ACollector> gc) noexcept;
-#endif
             /** update gc-aware exit pointers from this ParserStateMachine **/
             void forward_children(obj<ACollector> gc) noexcept;
 
diff --git a/src/reader2/ParserStateMachine.cpp b/src/reader2/ParserStateMachine.cpp
index 984841b5..c3d92a0c 100644
--- a/src/reader2/ParserStateMachine.cpp
+++ b/src/reader2/ParserStateMachine.cpp
@@ -897,19 +897,12 @@ namespace xo {
         // ----- gc support -----
 
 #ifdef OBSOLETE
-        std::size_t
-        ParserStateMachine::shallow_size() const noexcept
+        void
+        ParserStateMachine::shallow_copy(obj<ACollector> gc) noexcept
         {
-            return sizeof(ParserStateMachine);
-        }
-
-        ParserStateMachine *
-        ParserStateMachine::shallow_copy(obj<AAllocator> mm) const noexcept
-        {
-            (void)mm;
+            (void)gc;
 
             assert(false);
-            return nullptr;
         }
 #endif