diff --git a/src/flash_registry_win.cc b/src/flash_registry_win.cc
index 7906ee25a..f9c58dd99 100644
--- a/src/flash_registry_win.cc
+++ b/src/flash_registry_win.cc
@@ -22,40 +22,79 @@
 
 namespace toit {
 
+static const int ALLOCATION_SIZE = 2 * MB;
+static const int ENCRYPTION_WRITE_SIZE = 16;
+
+// An aligned (FLASH_BASED_SIZE) view into the allocations_malloced.
 const char* FlashRegistry::allocations_memory_ = null;
+static void* allocations_malloced = null;
 
 void FlashRegistry::set_up() {
+  ASSERT(allocations_malloced == null);
+  ASSERT(allocations_memory() == null);
+
+  allocations_malloced = malloc(ALLOCATION_SIZE + FLASH_PAGE_SIZE);
+  // Align the memory to FLASH_PAGE_SIZE.
+  // Note that we allocated FLASH_PAGE_SIZE more than necessary, so we could do this.
+  allocations_memory_ = Utils::round_up(unvoid_cast<char*>(allocations_malloced), FLASH_PAGE_SIZE);
 }
 
 void FlashRegistry::tear_down() {
+  allocations_memory_ = null;
+  free(allocations_malloced);
+  allocations_malloced = null;
 }
 
 bool FlashRegistry::is_allocations_set_up() {
-  return true;
+  return allocations_memory_ != null;
 }
 
 void FlashRegistry::flush() {
-  UNIMPLEMENTED();
+  // No flushing necessary.
 }
 
 int FlashRegistry::allocations_size() {
-  return 0;
+  return ALLOCATION_SIZE;
 }
 
 int FlashRegistry::erase_chunk(int offset, int size) {
-  UNIMPLEMENTED();
+  ASSERT(Utils::is_aligned(offset, FLASH_PAGE_SIZE));
+  size = Utils::round_up(size, FLASH_PAGE_SIZE);
+  memset(memory(offset, size), 0xff, size);
+  return size;
+}
+
+bool is_erased(void* memory, int offset, int size) {
+  char* dest = reinterpret_cast<char*>(memory);
+  for (int i = 0; i < size; i++) {
+    uint8 value = dest[i];
+    if (value != 0xff) {
+      return false;
+    }
+  }
+  return true;
 }
 
 bool FlashRegistry::write_chunk(const void* chunk, int offset, int size) {
-  UNIMPLEMENTED();
+  void* dest = memory(offset, size);
+  ASSERT(Utils::is_aligned(offset, ENCRYPTION_WRITE_SIZE));
+  ASSERT(Utils::is_aligned(size, ENCRYPTION_WRITE_SIZE));
+  ASSERT(is_erased(dest, 0, size));
+  memcpy(dest, chunk, size);
+  return true;
 }
 
 int FlashRegistry::offset(const void* cursor) {
-  UNIMPLEMENTED();
+  ASSERT(allocations_memory() != null);
+  word offset = Utils::address_distance(allocations_memory(), cursor);
+  ASSERT(0 <= offset && offset < allocations_size());
+  return offset;
 }
 
 bool FlashRegistry::erase_flash_registry() {
-  UNIMPLEMENTED();
+  ASSERT(allocations_memory() != null);
+  FlashRegistry::erase_chunk(0, allocations_size());
+  return true;
 }
 
 } // namespace toit
diff --git a/tests/fail.cmake b/tests/fail.cmake
index d1e638d00..072a88152 100644
--- a/tests/fail.cmake
+++ b/tests/fail.cmake
@@ -26,7 +26,6 @@ list(APPEND TOIT_SKIP_TESTS
 
 if ("${CMAKE_SYSTEM_NAME}" STREQUAL "Windows" OR "${CMAKE_SYSTEM_NAME}" STREQUAL "MSYS")
   list(APPEND TOIT_FAILING_TESTS
-    tests/containers_test.toit
     tests/time_test.toit
     tests/zlib_test.toit
     tests/class_field_limit_test_compiler.toit