diff --git a/include/xo/gc/DX1Collector.hpp b/include/xo/gc/DX1Collector.hpp
index 6139dbb..9ffe5fe 100644
--- a/include/xo/gc/DX1Collector.hpp
+++ b/include/xo/gc/DX1Collector.hpp
@@ -227,7 +227,7 @@ namespace xo {
             bool is_forwarding_header(header_type hdr) const noexcept;
 
             /** Retreive bookkeeping info for allocation at @p mem. **/
-            AllocInfo alloc_info(value_type mem) const noexcept;
+            AllocInfo alloc_info(void * mem) const noexcept;
 
             /** true iff type with id @p tseq has known metadata
              *  (i.e. has appeared in preceding call to install_type
diff --git a/include/xo/gc/detail/IGCObjectVisitor_DX1Collector.hpp b/include/xo/gc/detail/IGCObjectVisitor_DX1Collector.hpp
index 6512f88..ce01500 100644
--- a/include/xo/gc/detail/IGCObjectVisitor_DX1Collector.hpp
+++ b/include/xo/gc/detail/IGCObjectVisitor_DX1Collector.hpp
@@ -45,6 +45,9 @@ namespace xo {
             /** @defgroup mm-gcobjectvisitor-dx1collector-methods **/
             ///@{
             // const methods
+            /** allocation metadata for gc-aware data at address @p gco.
+@p gco must be the result of a call to collector's alloc() function **/
+            static AllocInfo alloc_info(const DX1Collector & self, void * addr);
 
             // non-const methods
             /** allocate copy of source object at address @p src.
diff --git a/src/gc/DX1Collector.cpp b/src/gc/DX1Collector.cpp
index d6d889f..9075f44 100644
--- a/src/gc/DX1Collector.cpp
+++ b/src/gc/DX1Collector.cpp
@@ -350,8 +350,8 @@ namespace xo {
         }
 
         AllocInfo
-        DX1Collector::alloc_info(value_type mem) const noexcept {
-            return gco_store_.alloc_info(mem);
+        DX1Collector::alloc_info(void * mem) const noexcept {
+            return gco_store_.alloc_info((std::byte *)(mem));
         }
 
         bool
diff --git a/src/gc/facet/IGCObjectVisitor_DX1Collector.cpp b/src/gc/facet/IGCObjectVisitor_DX1Collector.cpp
index d4c609c..5dd9d3d 100644
--- a/src/gc/facet/IGCObjectVisitor_DX1Collector.cpp
+++ b/src/gc/facet/IGCObjectVisitor_DX1Collector.cpp
@@ -15,6 +15,12 @@
 
 namespace xo {
     namespace mm {
+        auto
+        IGCObjectVisitor_DX1Collector::alloc_info(const DX1Collector & self, void * addr) -> AllocInfo
+        {
+            return self.alloc_info(addr);
+        }
+
         auto
         IGCObjectVisitor_DX1Collector::alloc_copy(DX1Collector & self, std::byte * src) -> void *
         {