diff --git a/fs_mgr/libsnapshot/cow_writer.cpp b/fs_mgr/libsnapshot/cow_writer.cpp
index 51c00a9..0a7ceab 100644
--- a/fs_mgr/libsnapshot/cow_writer.cpp
+++ b/fs_mgr/libsnapshot/cow_writer.cpp
@@ -58,6 +58,12 @@
     return EmitRawBlocks(new_block_start, data, size);
 }
 
+bool AddXorBlocks(uint32_t /*new_block_start*/, const void* /*data*/, size_t /*size*/,
+                  uint32_t /*old_block*/, uint16_t /*offset*/) {
+    LOG(ERROR) << "AddXorBlocks not yet implemented";
+    return false;
+}
+
 bool ICowWriter::AddZeroBlocks(uint64_t new_block_start, uint64_t num_blocks) {
     uint64_t last_block = new_block_start + num_blocks - 1;
     if (!ValidateNewBlock(last_block)) {
@@ -70,6 +76,11 @@
     return EmitLabel(label);
 }
 
+bool AddSequenceData(size_t /*num_ops*/, const uint32_t* /*data*/) {
+    LOG(ERROR) << "AddSequenceData not yet implemented";
+    return false;
+}
+
 bool ICowWriter::ValidateNewBlock(uint64_t new_block) {
     if (options_.max_blocks && new_block >= options_.max_blocks.value()) {
         LOG(ERROR) << "New block " << new_block << " exceeds maximum block count "
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
index f43ea68..fbe6461 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
@@ -55,12 +55,19 @@
     // Encode a sequence of raw blocks. |size| must be a multiple of the block size.
     bool AddRawBlocks(uint64_t new_block_start, const void* data, size_t size);
 
+    // Add a sequence of xor'd blocks. |size| must be a multiple of the block size.
+    bool AddXorBlocks(uint32_t new_block_start, const void* data, size_t size, uint32_t old_block,
+                      uint16_t offset);
+
     // Encode a sequence of zeroed blocks. |size| must be a multiple of the block size.
     bool AddZeroBlocks(uint64_t new_block_start, uint64_t num_blocks);
 
     // Add a label to the op sequence.
     bool AddLabel(uint64_t label);
 
+    // Add sequence data for op merging. Data is a list of the destination block numbers.
+    bool AddSequenceData(size_t num_ops, const uint32_t* data);
+
     // Flush all pending writes. This must be called before closing the writer
     // to ensure that the correct headers and footers are written.
     virtual bool Finalize() = 0;