diff --git a/src/backend/backend.h b/src/backend/backend.h
index 36328f4..1cc9c0b 100644
--- a/src/backend/backend.h
+++ b/src/backend/backend.h
@@ -87,6 +87,8 @@ namespace snmalloc
         return {p, nullptr};
       }
 
+      meta->meta_common.chunk = p;
+
       MetaEntry t(meta, remote, sizeclass);
       Pagemap::set_metaentry(local_state, address_cast(p), size, t);
       return {p, meta};
diff --git a/src/mem/corealloc.h b/src/mem/corealloc.h
index 98c80a8..b0fc28e 100644
--- a/src/mem/corealloc.h
+++ b/src/mem/corealloc.h
@@ -321,13 +321,16 @@ namespace snmalloc
       // have the whole chunk.
       auto start_of_slab = pointer_align_down<void>(
         p, snmalloc::sizeclass_to_slab_size(sizeclass));
-      // TODO Add bounds correctly here
-      chunk_record->meta_common.chunk =
-        capptr::Chunk<void>(start_of_slab.unsafe_ptr());
+
+      SNMALLOC_ASSERT(
+        address_cast(start_of_slab) ==
+        address_cast(chunk_record->meta_common.chunk));
 
 #ifdef SNMALLOC_TRACING
       std::cout << "Slab " << start_of_slab.unsafe_ptr()
                 << " is unused, Object sizeclass " << sizeclass << std::endl;
+#else
+      UNUSED(start_of_slab);
 #endif
       return chunk_record;
     }
diff --git a/src/mem/localalloc.h b/src/mem/localalloc.h
index 1e62123..db4bbfa 100644
--- a/src/mem/localalloc.h
+++ b/src/mem/localalloc.h
@@ -536,15 +536,10 @@ namespace snmalloc
 
         ChunkRecord* slab_record =
           reinterpret_cast<ChunkRecord*>(entry.get_metaslab());
-        /*
-         * StrictProvenance TODO: this is a subversive amplification.  p_tame is
-         * tame but Alloc-bounded, but we're coercing it to Chunk-bounded.  We
-         * should, instead, not be storing ->chunk here, but should be keeping
-         * a CapPtr<void, Chunk> to this region internally even while it's
-         * allocated.
-         */
-        slab_record->meta_common.chunk =
-          capptr::Chunk<void>(p_tame.unsafe_ptr());
+
+        SNMALLOC_ASSERT(
+          address_cast(slab_record->meta_common.chunk) == address_cast(p_tame));
+
         check_init(
           [](
             CoreAlloc* core_alloc,
diff --git a/src/mem/metaslab.h b/src/mem/metaslab.h
index 997439b..1057c14 100644
--- a/src/mem/metaslab.h
+++ b/src/mem/metaslab.h
@@ -9,6 +9,13 @@
 
 namespace snmalloc
 {
+  /**
+   * A guaranteed type-stable sub-structure of all metadata referenced by the
+   * Pagemap.  Use-specific structures (Metaslab, ChunkRecord) are expected to
+   * have this at offset zero so that, even in the face of concurrent mutation
+   * and reuse of the memory backing that metadata, the types of these fields
+   * remain fixed.
+   */
   struct MetaCommon
   {
     capptr::Chunk<void> chunk;
@@ -18,6 +25,8 @@ namespace snmalloc
   class alignas(CACHELINE_SIZE) Metaslab
   {
   public:
+    MetaCommon meta_common;
+
     // Used to link metaslabs together in various other data-structures.
     Metaslab* next{nullptr};
 
@@ -186,6 +195,11 @@ namespace snmalloc
     }
   };
 
+  static_assert(std::is_standard_layout_v<Metaslab>);
+  static_assert(
+    offsetof(Metaslab, meta_common) == 0,
+    "ChunkRecord and Metaslab must share a common prefix");
+
   /**
    * Entry stored in the pagemap.
    */