diff --git a/src/snmalloc/mem/corealloc.h b/src/snmalloc/mem/corealloc.h
index 4ad27a8ef..69c43335f 100644
--- a/src/snmalloc/mem/corealloc.h
+++ b/src/snmalloc/mem/corealloc.h
@@ -831,8 +831,8 @@ namespace snmalloc
       return meta->return_objects(length);
     }
 
-    template<ZeroMem zero_mem>
-    SNMALLOC_SLOW_PATH capptr::Alloc<void>
+    template<ZeroMem zero_mem, typename CheckInit>
+    SNMALLOC_FAST_PATH capptr::Alloc<void>
     small_alloc(smallsizeclass_t sizeclass, freelist::Iter<>& fast_free_list)
     {
       void* result = SecondaryAllocator::allocate(
@@ -842,7 +842,18 @@ namespace snmalloc
         });
 
       if (result != nullptr)
-        return capptr::Alloc<void>::unsafe_from(result);
+      {
+        if constexpr (zero_mem == YesZero)
+          Config::Pal::zero(result, sizeclass_to_size(sizeclass));
+
+        return CheckInit::check_init(
+          [result]() { return capptr::Alloc<void>::unsafe_from(result); },
+          [](Allocator*, void* result) {
+            return capptr::Alloc<void>::unsafe_from(result);
+          },
+          result);
+      }
+
       // Look to see if we can grab a free list.
       auto& sl = alloc_classes[sizeclass].available;
       if (SNMALLOC_LIKELY(alloc_classes[sizeclass].length > 0))
@@ -853,7 +864,8 @@ namespace snmalloc
           if (SNMALLOC_UNLIKELY(alloc_classes[sizeclass].length == 1))
           {
             if (entropy.next_bit() == 0)
-              return small_alloc_slow<zero_mem>(sizeclass, fast_free_list);
+              return small_alloc_slow<zero_mem, CheckInit>(
+                sizeclass, fast_free_list);
           }
         }
 
@@ -884,7 +896,7 @@ namespace snmalloc
         auto r = finish_alloc<zero_mem, Config>(p, sizeclass);
         return ticker.check_tick(r);
       }
-      return small_alloc_slow<zero_mem>(sizeclass, fast_free_list);
+      return small_alloc_slow<zero_mem, CheckInit>(sizeclass, fast_free_list);
     }
 
     /**
@@ -905,57 +917,66 @@ namespace snmalloc
       }
     }
 
-    template<ZeroMem zero_mem>
+    template<ZeroMem zero_mem, typename CheckInit>
     SNMALLOC_SLOW_PATH capptr::Alloc<void> small_alloc_slow(
       smallsizeclass_t sizeclass, freelist::Iter<>& fast_free_list)
     {
-      size_t rsize = sizeclass_to_size(sizeclass);
+      return CheckInit::check_init(
+        [this, sizeclass, &fast_free_list]() -> capptr::Alloc<void> {
+          size_t rsize = sizeclass_to_size(sizeclass);
 
-      // No existing free list get a new slab.
-      size_t slab_size = sizeclass_to_slab_size(sizeclass);
+          // No existing free list get a new slab.
+          size_t slab_size = sizeclass_to_slab_size(sizeclass);
 
 #ifdef SNMALLOC_TRACING
-      message<1024>("small_alloc_slow rsize={} slab size={}", rsize, slab_size);
+          message<1024>(
+            "small_alloc_slow rsize={} slab size={}", rsize, slab_size);
 #endif
 
-      auto [slab, meta] = Config::Backend::alloc_chunk(
-        get_backend_local_state(),
-        slab_size,
-        PagemapEntry::encode(
-          public_state(), sizeclass_t::from_small_class(sizeclass)),
-        sizeclass_t::from_small_class(sizeclass));
+          auto [slab, meta] = Config::Backend::alloc_chunk(
+            get_backend_local_state(),
+            slab_size,
+            PagemapEntry::encode(
+              public_state(), sizeclass_t::from_small_class(sizeclass)),
+            sizeclass_t::from_small_class(sizeclass));
 
-      if (slab == nullptr)
-      {
-        return nullptr;
-      }
+          if (slab == nullptr)
+          {
+            return nullptr;
+          }
 
-      // Set meta slab to empty.
-      meta->initialise(
-        sizeclass, address_cast(slab), freelist::Object::key_root);
+          // Set meta slab to empty.
+          meta->initialise(
+            sizeclass, address_cast(slab), freelist::Object::key_root);
 
-      // Build a free list for the slab
-      alloc_new_list(slab, meta, rsize, slab_size, entropy);
+          // Build a free list for the slab
+          alloc_new_list(slab, meta, rsize, slab_size, entropy);
 
-      auto domesticate =
-        [this](freelist::QueuePtr p) SNMALLOC_FAST_PATH_LAMBDA {
-          return capptr_domesticate<Config>(backend_state_ptr(), p);
-        };
-      auto [p, still_active] = BackendSlabMetadata::alloc_free_list(
-        domesticate, meta, fast_free_list, entropy, sizeclass);
+          auto domesticate =
+            [this](freelist::QueuePtr p) SNMALLOC_FAST_PATH_LAMBDA {
+              return capptr_domesticate<Config>(backend_state_ptr(), p);
+            };
+          auto [p, still_active] = BackendSlabMetadata::alloc_free_list(
+            domesticate, meta, fast_free_list, entropy, sizeclass);
 
-      if (still_active)
-      {
-        alloc_classes[sizeclass].length++;
-        alloc_classes[sizeclass].available.insert(meta);
-      }
-      else
-      {
-        laden.insert(meta);
-      }
+          if (still_active)
+          {
+            alloc_classes[sizeclass].length++;
+            alloc_classes[sizeclass].available.insert(meta);
+          }
+          else
+          {
+            laden.insert(meta);
+          }
 
-      auto r = finish_alloc<zero_mem, Config>(p, sizeclass);
-      return ticker.check_tick(r);
+          auto r = finish_alloc<zero_mem, Config>(p, sizeclass);
+          return ticker.check_tick(r);
+        },
+        [](Allocator* a, smallsizeclass_t sizeclass) {
+          return a->small_alloc<zero_mem, CheckInitNoOp>(
+            sizeclass_to_size(sizeclass));
+        },
+        sizeclass);
     }
 
     template<ZeroMem zero_mem, typename Slowpath, typename Domesticator>
@@ -1136,23 +1157,14 @@ namespace snmalloc
         return finish_alloc<zero_mem, Config>(p, sizeclass);
       }
 
-      return CheckInit::check_init(
-        [this, sizeclass, fl]() -> capptr::Alloc<void> {
-          return handle_message_queue(
-            [](
-              Allocator* alloc,
-              smallsizeclass_t sizeclass,
-              freelist::Iter<>* fl) -> capptr::Alloc<void> {
-              return alloc->small_alloc<zero_mem>(sizeclass, *fl);
-            },
-            this,
-            sizeclass,
-            fl);
-        },
-        [](Allocator* a, size_t size) {
-          return a->template small_alloc<zero_mem, CheckInitNoOp>(size);
+      return handle_message_queue(
+        [](Allocator* alloc, smallsizeclass_t sizeclass, freelist::Iter<>* fl)
+          -> capptr::Alloc<void> {
+          return alloc->small_alloc<zero_mem, CheckInit>(sizeclass, *fl);
         },
-        size);
+        this,
+        sizeclass,
+        fl);
     }
 
     /**