diff --git a/include/xo/gc/GCObjectStore.hpp b/include/xo/gc/GCObjectStore.hpp
index 9e9c560..83aec4e 100644
--- a/include/xo/gc/GCObjectStore.hpp
+++ b/include/xo/gc/GCObjectStore.hpp
@@ -7,7 +7,6 @@
 
 #include "GCObjectStoreConfig.hpp"
 #include "ObjectTypeSlot.hpp"
-//#include "Generation.hpp"
 #include "object_age.hpp"
 #include <xo/alloc2/role.hpp>
 #include <array>
@@ -15,6 +14,7 @@
 namespace xo {
     namespace mm {
         class DX1Collector;
+        class X1VerifyStats;
 
         /** @brief container to hold gc-aware objects for X1 collector
          **/
@@ -115,12 +115,28 @@ namespace xo {
              **/
             GCMoveCheckpoint snap_move_checkpoint(Generation upto);
 
+            /** verify consistency of this object store, on behalf of collector @p gc.
+             *  Advancing counters in @p *p_verify_stats.
+             *
+             *  @p gc argument is load-bearing so we have collector interface
+             *  to call AGCObject visitor method (forward_children()) on each
+             *  object stored here.
+             **/
+            void verify_ok(DX1Collector * gc,
+                           X1VerifyStats * p_verify_stats) noexcept;
+
             /** Register object type with this collector.
              *  Provides shallow copy and pointer forwarding for instances of this
              *  type.
              **/
             bool install_type(const AGCObject & meta) noexcept;
 
+            /** For each generation g in [0 ,.., upto)
+             *  swap arenas assigned to {to-space, from-space}.
+             *  Invoked once at the beginning of each gc cycle.
+             **/
+            void swap_roles(Generation upto) noexcept;
+
             /** move subgraph at @p root to to-space on behalf of collector @p gc
              *  Special behavior relative to @ref _deep_move_interior :
              *  If @p root is not in gc-space, visit immediate children and move them in place (!).
@@ -131,12 +147,6 @@ namespace xo {
                                   obj<AGCObject> from_src,
                                   Generation upto);
 
-            /** For each generation g in [0 ,.., upto)
-             *  swap arenas assigned to {to-space, from-space}.
-             *  Invoked once at the beginning of each gc cycle.
-             **/
-            void swap_roles(Generation upto) noexcept;
-
             /** move interior subgraph at @p from_src to to-space.
              *  no-op if not in gc-space.
              *
diff --git a/src/gc/DX1Collector.cpp b/src/gc/DX1Collector.cpp
index 795cd2f..b589bcd 100644
--- a/src/gc/DX1Collector.cpp
+++ b/src/gc/DX1Collector.cpp
@@ -416,39 +416,7 @@ namespace xo {
                 }
 
                 // 3. scan to-space for each generation
-                for (Generation g(0); g < config_.n_generation_; ++g) {
-                    const DArena * space = this->get_space(role::to_space(), g);
-
-                    for (const AllocInfo & info : *space) {
-
-                        if (info.is_forwarding_tseq()) {
-                            ++verify_stats_.n_fwd_;
-
-                        } else {
-                            typeseq tseq(info.tseq());
-
-                            const AGCObject * iface = this->lookup_type(tseq);
-
-                            if (iface && !(iface->_has_null_vptr())) {
-                                const void * data = info.payload().first;
-
-                                // assembled fop for gc-aware object
-                                obj<AGCObject> gco(iface, const_cast<void *>(data));
-
-                                // forward_children is hijacked here to verify
-                                // child pointer validity.
-                                //
-                                // Nested control reenters
-                                // X1Collector::forward_inplace() -> _verify_aux()
-                                //
-                                gco.forward_children(self);
-                            } else {
-                                ++verify_stats_.n_no_iface_;
-                                continue;
-                            }
-                        }
-                    }
-                }
+                gco_store_.verify_ok(this, &(this->verify_stats_));
 
                 // 4. scan mutation logs
                 mlog_store_.verify_ok(&gco_store_,
diff --git a/src/gc/GCObjectStore.cpp b/src/gc/GCObjectStore.cpp
index 573af2e..df897e3 100644
--- a/src/gc/GCObjectStore.cpp
+++ b/src/gc/GCObjectStore.cpp
@@ -682,6 +682,45 @@ namespace xo {
             return gray_lo_v;
         }
 
+        void
+        GCObjectStore::verify_ok(DX1Collector * gc,
+                                 X1VerifyStats * p_verify_stats) noexcept
+        {
+            for (Generation g(0); g < config_.n_generation_; ++g) {
+                const DArena * space = this->get_space(role::to_space(), g);
+
+                for (const AllocInfo & info : *space) {
+
+                    if (info.is_forwarding_tseq()) {
+                        ++(p_verify_stats->n_fwd_);
+
+                    } else {
+                        typeseq tseq(info.tseq());
+
+                        const AGCObject * iface = this->lookup_type(tseq);
+
+                        if (iface && !(iface->_has_null_vptr())) {
+                            const void * data = info.payload().first;
+
+                            // assembled fop for gc-aware object
+                            obj<AGCObject> gco(iface, const_cast<void *>(data));
+
+                            // forward_children is hijacked here to verify
+                            // child pointer validity.
+                            //
+                            // Nested control reenters
+                            // X1Collector::forward_inplace() -> _verify_aux()
+                            //
+                            gco.forward_children(gc->ref<ACollector>());
+                        } else {
+                            ++(p_verify_stats->n_no_iface_);
+                            continue;
+                        }
+                    }
+                }
+            }
+        }
+
         /* editor bait: register_type */
         bool
         GCObjectStore::install_type(const AGCObject & meta) noexcept