diff --git a/extras/tests/Helpers/Allocators.hpp b/extras/tests/Helpers/Allocators.hpp
index a4b0793a2..6d35b3a9a 100644
--- a/extras/tests/Helpers/Allocators.hpp
+++ b/extras/tests/Helpers/Allocators.hpp
@@ -37,24 +37,27 @@ class AllocatorLog {
   };
 
   struct Reallocate {
-    Reallocate(size_t s) : size(s) {}
-    size_t size;
+    Reallocate(size_t s1, size_t s2) : oldSize(s1), newSize(s2) {}
+    size_t oldSize, newSize;
   };
 
-  struct Deallocate {};
+  struct Deallocate {
+    Deallocate(size_t s) : size(s) {}
+    size_t size;
+  };
 
   AllocatorLog& operator<<(const Allocate& a) {
     _log << "allocate(" << a.size << ")\n";
     return *this;
   }
 
-  AllocatorLog& operator<<(const Deallocate&) {
-    _log << "deallocate()\n";
+  AllocatorLog& operator<<(const Deallocate& d) {
+    _log << "deallocate(" << d.size << ")\n";
     return *this;
   }
 
   AllocatorLog& operator<<(const Reallocate& a) {
-    _log << "reallocate(" << a.size << ")\n";
+    _log << "reallocate(" << a.oldSize << ", " << a.newSize << ")\n";
     return *this;
   }
 
@@ -83,17 +86,25 @@ class SpyingAllocator : public ArduinoJson::Allocator {
 
   void* allocate(size_t n) override {
     _log << AllocatorLog::Allocate(n);
-    return malloc(n);
+    auto block = reinterpret_cast<AllocatedBlock*>(
+        malloc(sizeof(AllocatedBlock) + n - 1));
+    block->size = n;
+    return block->payload;
   }
 
   void deallocate(void* p) override {
-    _log << AllocatorLog::Deallocate();
-    free(p);
+    auto block = AllocatedBlock::fromPayload(p);
+    _log << AllocatorLog::Deallocate(block->size);
+    free(block);
   }
 
-  void* reallocate(void* ptr, size_t n) override {
-    _log << AllocatorLog::Reallocate(n);
-    return realloc(ptr, n);
+  void* reallocate(void* p, size_t n) override {
+    auto block = AllocatedBlock::fromPayload(p);
+    _log << AllocatorLog::Reallocate(block->size, n);
+    block = reinterpret_cast<AllocatedBlock*>(
+        realloc(block, sizeof(AllocatedBlock) + n - 1));
+    block->size = n;
+    return block->payload;
   }
 
   const AllocatorLog& log() const {
@@ -101,5 +112,15 @@ class SpyingAllocator : public ArduinoJson::Allocator {
   }
 
  private:
+  struct AllocatedBlock {
+    size_t size;
+    char payload[1];
+
+    static AllocatedBlock* fromPayload(void* p) {
+      return reinterpret_cast<AllocatedBlock*>(
+          reinterpret_cast<char*>(p) - offsetof(AllocatedBlock, payload));
+    }
+  };
+
   AllocatorLog _log;
 };
diff --git a/extras/tests/JsonDocument/allocator.cpp b/extras/tests/JsonDocument/allocator.cpp
index 472b08307..62be1ce53 100644
--- a/extras/tests/JsonDocument/allocator.cpp
+++ b/extras/tests/JsonDocument/allocator.cpp
@@ -44,7 +44,7 @@ TEST_CASE("JsonDocument's allocator") {
     { JsonDocument doc(4096, &spyingAllocator); }
     REQUIRE(spyingAllocator.log() == AllocatorLog()
                                          << AllocatorLog::Allocate(4096)
-                                         << AllocatorLog::Deallocate());
+                                         << AllocatorLog::Deallocate(4096));
   }
 
   SECTION("Copy construct") {
@@ -61,8 +61,8 @@ TEST_CASE("JsonDocument's allocator") {
     REQUIRE(spyingAllocator.log() == AllocatorLog()
                                          << AllocatorLog::Allocate(4096)
                                          << AllocatorLog::Allocate(4096)
-                                         << AllocatorLog::Deallocate()
-                                         << AllocatorLog::Deallocate());
+                                         << AllocatorLog::Deallocate(4096)
+                                         << AllocatorLog::Deallocate(4096));
   }
 
   SECTION("Move construct") {
@@ -79,7 +79,7 @@ TEST_CASE("JsonDocument's allocator") {
     }
     REQUIRE(spyingAllocator.log() == AllocatorLog()
                                          << AllocatorLog::Allocate(4096)
-                                         << AllocatorLog::Deallocate());
+                                         << AllocatorLog::Deallocate(4096));
   }
 
   SECTION("Copy assign larger") {
@@ -97,10 +97,10 @@ TEST_CASE("JsonDocument's allocator") {
     REQUIRE(spyingAllocator.log() == AllocatorLog()
                                          << AllocatorLog::Allocate(4096)
                                          << AllocatorLog::Allocate(8)
-                                         << AllocatorLog::Deallocate()
+                                         << AllocatorLog::Deallocate(8)
                                          << AllocatorLog::Allocate(4096)
-                                         << AllocatorLog::Deallocate()
-                                         << AllocatorLog::Deallocate());
+                                         << AllocatorLog::Deallocate(4096)
+                                         << AllocatorLog::Deallocate(4096));
   }
 
   SECTION("Copy assign smaller") {
@@ -118,10 +118,10 @@ TEST_CASE("JsonDocument's allocator") {
     REQUIRE(spyingAllocator.log() == AllocatorLog()
                                          << AllocatorLog::Allocate(1024)
                                          << AllocatorLog::Allocate(4096)
-                                         << AllocatorLog::Deallocate()
+                                         << AllocatorLog::Deallocate(4096)
                                          << AllocatorLog::Allocate(1024)
-                                         << AllocatorLog::Deallocate()
-                                         << AllocatorLog::Deallocate());
+                                         << AllocatorLog::Deallocate(1024)
+                                         << AllocatorLog::Deallocate(1024));
   }
 
   SECTION("Copy assign same size") {
@@ -139,8 +139,8 @@ TEST_CASE("JsonDocument's allocator") {
     REQUIRE(spyingAllocator.log() == AllocatorLog()
                                          << AllocatorLog::Allocate(1024)
                                          << AllocatorLog::Allocate(1024)
-                                         << AllocatorLog::Deallocate()
-                                         << AllocatorLog::Deallocate());
+                                         << AllocatorLog::Deallocate(1024)
+                                         << AllocatorLog::Deallocate(1024));
   }
 
   SECTION("Move assign") {
@@ -159,8 +159,8 @@ TEST_CASE("JsonDocument's allocator") {
     REQUIRE(spyingAllocator.log() == AllocatorLog()
                                          << AllocatorLog::Allocate(4096)
                                          << AllocatorLog::Allocate(8)
-                                         << AllocatorLog::Deallocate()
-                                         << AllocatorLog::Deallocate());
+                                         << AllocatorLog::Deallocate(8)
+                                         << AllocatorLog::Deallocate(4096));
   }
 
   SECTION("garbageCollect()") {