diff --git a/test/implementations/onblocks/datanodestore/DataInnerNodeTest.cpp b/test/implementations/onblocks/datanodestore/DataInnerNodeTest.cpp
index 14e61b76..6696492a 100644
--- a/test/implementations/onblocks/datanodestore/DataInnerNodeTest.cpp
+++ b/test/implementations/onblocks/datanodestore/DataInnerNodeTest.cpp
@@ -95,7 +95,7 @@ public:
   }
 
   Key InitializeInnerNodeAddLeafReturnKey() {
-    auto node = DataInnerNode::InitializeNewNode(blockStore->create(BLOCKSIZE_BYTES), *leaf);
+    auto node = DataInnerNode::InitializeNewNode(blockStore->create(Data(BLOCKSIZE_BYTES)), *leaf);
     AddALeafTo(node.get());
     return node->key();
   }
@@ -111,14 +111,14 @@ public:
 constexpr uint32_t DataInnerNodeTest::BLOCKSIZE_BYTES;
 
 TEST_F(DataInnerNodeTest, CorrectKeyReturnedAfterInitialization) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   Key key = block->key();
   auto node = DataInnerNode::InitializeNewNode(std::move(block), *leaf);
   EXPECT_EQ(key, node->key());
 }
 
 TEST_F(DataInnerNodeTest, CorrectKeyReturnedAfterLoading) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   Key key = block->key();
   DataInnerNode::InitializeNewNode(std::move(block), *leaf);
 
@@ -127,7 +127,7 @@ TEST_F(DataInnerNodeTest, CorrectKeyReturnedAfterLoading) {
 }
 
 TEST_F(DataInnerNodeTest, InitializesCorrectly) {
-  auto node = DataInnerNode::InitializeNewNode(blockStore->create(BLOCKSIZE_BYTES), *leaf);
+  auto node = DataInnerNode::InitializeNewNode(blockStore->create(Data(BLOCKSIZE_BYTES)), *leaf);
 
   EXPECT_EQ(1u, node->numChildren());
   EXPECT_EQ(leaf->key(), node->getChild(0)->key());
diff --git a/test/implementations/onblocks/datanodestore/DataLeafNodeTest.cpp b/test/implementations/onblocks/datanodestore/DataLeafNodeTest.cpp
index 265be219..283c772e 100644
--- a/test/implementations/onblocks/datanodestore/DataLeafNodeTest.cpp
+++ b/test/implementations/onblocks/datanodestore/DataLeafNodeTest.cpp
@@ -100,7 +100,7 @@ public:
   }
 
   Key InitializeLeafGrowAndReturnKey() {
-    auto leaf = DataLeafNode::InitializeNewNode(blockStore->create(BLOCKSIZE_BYTES));
+    auto leaf = DataLeafNode::InitializeNewNode(blockStore->create(Data(BLOCKSIZE_BYTES)));
     leaf->resize(5);
     return leaf->key();
   }
@@ -117,14 +117,14 @@ constexpr uint32_t DataLeafNodeTest::BLOCKSIZE_BYTES;
 constexpr DataNodeLayout DataLeafNodeTest::LAYOUT;
 
 TEST_F(DataLeafNodeTest, CorrectKeyReturnedAfterInitialization) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   Key key = block->key();
   auto node = DataLeafNode::InitializeNewNode(std::move(block));
   EXPECT_EQ(key, node->key());
 }
 
 TEST_F(DataLeafNodeTest, CorrectKeyReturnedAfterLoading) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   Key key = block->key();
   DataLeafNode::InitializeNewNode(std::move(block));
 
@@ -133,7 +133,7 @@ TEST_F(DataLeafNodeTest, CorrectKeyReturnedAfterLoading) {
 }
 
 TEST_F(DataLeafNodeTest, InitializesCorrectly) {
-  auto leaf = DataLeafNode::InitializeNewNode(blockStore->create(BLOCKSIZE_BYTES));
+  auto leaf = DataLeafNode::InitializeNewNode(blockStore->create(Data(BLOCKSIZE_BYTES)));
   EXPECT_EQ(0u, leaf->numBytes());
 }
 
diff --git a/test/implementations/onblocks/datanodestore/DataNodeStoreTest.cpp b/test/implementations/onblocks/datanodestore/DataNodeStoreTest.cpp
index e804bc37..c07fd8ec 100644
--- a/test/implementations/onblocks/datanodestore/DataNodeStoreTest.cpp
+++ b/test/implementations/onblocks/datanodestore/DataNodeStoreTest.cpp
@@ -16,6 +16,7 @@ using std::string;
 using blockstore::BlockStore;
 using blockstore::testfake::FakeBlockStore;
 using blockstore::Key;
+using blockstore::Data;
 using namespace blobstore;
 using namespace blobstore::onblocks;
 using namespace blobstore::onblocks::datanodestore;
@@ -73,7 +74,7 @@ TEST_F(DataNodeStoreTest, InnerNodeWithDepth2IsRecognizedAfterStoreAndLoad) {
 }
 
 TEST_F(DataNodeStoreTest, DataNodeCrashesOnLoadIfDepthIsTooHigh) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   Key key = block->key();
   {
     DataNodeView view(std::move(block));
diff --git a/test/implementations/onblocks/datanodestore/DataNodeViewTest.cpp b/test/implementations/onblocks/datanodestore/DataNodeViewTest.cpp
index dc8dbb88..c576d4e8 100644
--- a/test/implementations/onblocks/datanodestore/DataNodeViewTest.cpp
+++ b/test/implementations/onblocks/datanodestore/DataNodeViewTest.cpp
@@ -15,6 +15,7 @@ using std::string;
 
 using blockstore::BlockStore;
 using blockstore::testfake::FakeBlockStore;
+using blockstore::Data;
 using namespace blobstore;
 using namespace blobstore::onblocks;
 using namespace blobstore::onblocks::datanodestore;
@@ -32,7 +33,7 @@ class DataNodeViewDepthTest: public DataNodeViewTest, public WithParamInterface<
 INSTANTIATE_TEST_CASE_P(DataNodeViewDepthTest, DataNodeViewDepthTest, Values(0, 1, 3, 10, 100));
 
 TEST_P(DataNodeViewDepthTest, DepthIsStored) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   auto key = block->key();
   {
     DataNodeView view(std::move(block));
@@ -47,7 +48,7 @@ class DataNodeViewSizeTest: public DataNodeViewTest, public WithParamInterface<u
 INSTANTIATE_TEST_CASE_P(DataNodeViewSizeTest, DataNodeViewSizeTest, Values(0, 50, 64, 1024, 1024*1024*1024));
 
 TEST_P(DataNodeViewSizeTest, SizeIsStored) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   auto key = block->key();
   {
     DataNodeView view(std::move(block));
@@ -59,7 +60,7 @@ TEST_P(DataNodeViewSizeTest, SizeIsStored) {
 
 TEST_F(DataNodeViewTest, DataIsStored) {
   DataBlockFixture randomData(DATASIZE_BYTES);
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   auto key = block->key();
   {
     DataNodeView view(std::move(block));
@@ -71,7 +72,7 @@ TEST_F(DataNodeViewTest, DataIsStored) {
 
 TEST_F(DataNodeViewTest, HeaderAndBodyDontOverlap) {
   DataBlockFixture randomData(DATASIZE_BYTES);
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   auto key = block->key();
   {
     DataNodeView view(std::move(block));
@@ -86,7 +87,7 @@ TEST_F(DataNodeViewTest, HeaderAndBodyDontOverlap) {
 }
 
 TEST_F(DataNodeViewTest, DataBeginWorksWithOneByteEntries) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   uint8_t *blockBegin = (uint8_t*)block->data();
   DataNodeView view(std::move(block));
 
@@ -94,7 +95,7 @@ TEST_F(DataNodeViewTest, DataBeginWorksWithOneByteEntries) {
 }
 
 TEST_F(DataNodeViewTest, DataBeginWorksWithEightByteEntries) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   uint8_t *blockBegin = (uint8_t*)block->data();
   DataNodeView view(std::move(block));
 
@@ -102,7 +103,7 @@ TEST_F(DataNodeViewTest, DataBeginWorksWithEightByteEntries) {
 }
 
 TEST_F(DataNodeViewTest, DataEndWorksWithOneByteEntries) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   uint8_t *blockBegin = (uint8_t*)block->data();
   DataNodeView view(std::move(block));
 
@@ -110,7 +111,7 @@ TEST_F(DataNodeViewTest, DataEndWorksWithOneByteEntries) {
 }
 
 TEST_F(DataNodeViewTest, DataEndWorksWithEightByteEntries) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   uint8_t *blockBegin = (uint8_t*)block->data();
   DataNodeView view(std::move(block));
 
@@ -126,7 +127,7 @@ BOOST_STATIC_ASSERT_MSG(DataNodeViewTest::DATASIZE_BYTES % sizeof(SizedDataEntry
   "If this static assertion fails, please use a different size for SizedDataEntry.");
 
 TEST_F(DataNodeViewTest, DataBeginWorksWithStructEntries) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   uint8_t *blockBegin = (uint8_t*)block->data();
   DataNodeView view(std::move(block));
 
@@ -134,7 +135,7 @@ TEST_F(DataNodeViewTest, DataBeginWorksWithStructEntries) {
 }
 
 TEST_F(DataNodeViewTest, DataEndWorksWithStructByteEntries) {
-  auto block = blockStore->create(BLOCKSIZE_BYTES);
+  auto block = blockStore->create(Data(BLOCKSIZE_BYTES));
   uint8_t *blockBegin = (uint8_t*)block->data();
   DataNodeView view(std::move(block));