diff --git a/payload_generator/delta_diff_utils.cc b/payload_generator/delta_diff_utils.cc
index 16a8ad5..d3629ff 100644
--- a/payload_generator/delta_diff_utils.cc
+++ b/payload_generator/delta_diff_utils.cc
@@ -387,17 +387,18 @@
     new_visited_blocks.AddExtent(new_part.verity.fec_extent);
   }
 
-  TEST_AND_RETURN_FALSE(DeltaMovedAndZeroBlocks(
-      aops,
-      old_part.path,
-      new_part.path,
-      old_part.size / kBlockSize,
-      new_part.size / kBlockSize,
-      soft_chunk_blocks,
-      version,
-      blob_file,
-      &old_visited_blocks,
-      &new_visited_blocks));
+  ExtentRanges old_zero_blocks;
+  TEST_AND_RETURN_FALSE(DeltaMovedAndZeroBlocks(aops,
+                                                old_part.path,
+                                                new_part.path,
+                                                old_part.size / kBlockSize,
+                                                new_part.size / kBlockSize,
+                                                soft_chunk_blocks,
+                                                version,
+                                                blob_file,
+                                                &old_visited_blocks,
+                                                &new_visited_blocks,
+                                                &old_zero_blocks));
 
   bool puffdiff_allowed = version.OperationAllowed(InstallOperation::PUFFDIFF);
   map<string, FilesystemInterface::File> old_files_map;
@@ -450,7 +451,7 @@
       old_file_extents =
           FilterExtentRanges(old_file.extents, old_visited_blocks);
     else
-      old_file_extents = old_file.extents;
+      old_file_extents = FilterExtentRanges(old_file.extents, old_zero_blocks);
     old_visited_blocks.AddExtents(old_file_extents);
 
     file_delta_processors.emplace_back(old_part.path,
@@ -527,7 +528,8 @@
                              const PayloadVersion& version,
                              BlobFileWriter* blob_file,
                              ExtentRanges* old_visited_blocks,
-                             ExtentRanges* new_visited_blocks) {
+                             ExtentRanges* new_visited_blocks,
+                             ExtentRanges* old_zero_blocks) {
   vector<BlockMapping::BlockId> old_block_ids;
   vector<BlockMapping::BlockId> new_block_ids;
   TEST_AND_RETURN_FALSE(MapPartitionBlocks(old_part,
@@ -567,8 +569,9 @@
     // importantly, these could sometimes be blocks discarded in the SSD which
     // would read non-zero values.
     if (old_block_ids[block] == 0)
-      old_visited_blocks->AddBlock(block);
+      old_zero_blocks->AddBlock(block);
   }
+  old_visited_blocks->AddRanges(*old_zero_blocks);
 
   // The collection of blocks in the new partition with just zeros. This is a
   // common case for free-space that's also problematic for bsdiff, so we want
diff --git a/payload_generator/delta_diff_utils.h b/payload_generator/delta_diff_utils.h
index c1f62fc..2306572 100644
--- a/payload_generator/delta_diff_utils.h
+++ b/payload_generator/delta_diff_utils.h
@@ -70,7 +70,8 @@
                              const PayloadVersion& version,
                              BlobFileWriter* blob_file,
                              ExtentRanges* old_visited_blocks,
-                             ExtentRanges* new_visited_blocks);
+                             ExtentRanges* new_visited_blocks,
+                             ExtentRanges* old_zero_blocks);
 
 // For a given file |name| append operations to |aops| to produce it in the
 // |new_part|. The file will be split in chunks of |chunk_blocks| blocks each
diff --git a/payload_generator/delta_diff_utils_unittest.cc b/payload_generator/delta_diff_utils_unittest.cc
index f6677f1..63e7506 100644
--- a/payload_generator/delta_diff_utils_unittest.cc
+++ b/payload_generator/delta_diff_utils_unittest.cc
@@ -131,6 +131,7 @@
                                   uint32_t minor_version) {
     BlobFileWriter blob_file(blob_fd_, &blob_size_);
     PayloadVersion version(kChromeOSMajorPayloadVersion, minor_version);
+    ExtentRanges old_zero_blocks;
     return diff_utils::DeltaMovedAndZeroBlocks(&aops_,
                                                old_part_.path,
                                                new_part_.path,
@@ -140,7 +141,8 @@
                                                version,
                                                &blob_file,
                                                &old_visited_blocks_,
-                                               &new_visited_blocks_);
+                                               &new_visited_blocks_,
+                                               &old_zero_blocks);
   }
 
   // Old and new temporary partitions used in the tests. These are initialized