diff --git a/include/xo/gc/DX1Collector.hpp b/include/xo/gc/DX1Collector.hpp
index 195569d..555ef89 100644
--- a/include/xo/gc/DX1Collector.hpp
+++ b/include/xo/gc/DX1Collector.hpp
@@ -382,13 +382,13 @@ namespace xo {
              *  use to detect forwarding activity after visiting objects
              **/
             GCMoveCheckpoint _snap_move_checkpoint(Generation upto);
-#endif
 
             /** traverse objects allocated after @p ckp, to make sure their children
              *  are forwarded. Repeat until traverse doesn't find any unforwarded children
              **/
             void _forward_children_until_fixpoint(Generation upto,
                                                   const GCMoveCheckpoint & ckp);
+#endif
 
             /** Evacuate object at @p *lhs_data to to-space.
              *  Replace original with forwarding pointer to new location
diff --git a/src/gc/DX1Collector.cpp b/src/gc/DX1Collector.cpp
index d6c24ca..e1fbe59 100644
--- a/src/gc/DX1Collector.cpp
+++ b/src/gc/DX1Collector.cpp
@@ -820,6 +820,7 @@ namespace xo {
         }
 #endif
 
+#ifdef OSBOLETE
         void
         DX1Collector::_forward_children_until_fixpoint(Generation upto,
                                                        const GCMoveCheckpoint & gray_lo_v)
@@ -828,6 +829,7 @@ namespace xo {
 
             gco_store_._forward_children_until_fixpoint(this, upto, gray_lo_v);
         }
+#endif
 
         void
         DX1Collector::copy_roots(Generation upto) noexcept