diff --git a/tools/releasetools/blockimgdiff.py b/tools/releasetools/blockimgdiff.py
index d49112fd16..b5a8cf03c5 100644
--- a/tools/releasetools/blockimgdiff.py
+++ b/tools/releasetools/blockimgdiff.py
@@ -261,7 +261,8 @@ class HeapItem(object):
 # original image.
 
 class BlockImageDiff(object):
-  def __init__(self, tgt, src=None, threads=None, version=4):
+  def __init__(self, tgt, src=None, threads=None, version=4,
+               disable_imgdiff=False):
     if threads is None:
       threads = multiprocessing.cpu_count() // 2
       if threads == 0:
@@ -274,6 +275,7 @@ class BlockImageDiff(object):
     self._max_stashed_size = 0
     self.touched_src_ranges = RangeSet()
     self.touched_src_sha1 = None
+    self.disable_imgdiff = disable_imgdiff
 
     assert version in (1, 2, 3, 4)
 
@@ -704,6 +706,7 @@ class BlockImageDiff(object):
             # produces significantly smaller patches than bsdiff).
             # This is permissible if:
             #
+            #  - imgdiff is not disabled, and
             #  - the source and target files are monotonic (ie, the
             #    data is stored with blocks in increasing order), and
             #  - we haven't removed any blocks from the source set.
@@ -713,7 +716,7 @@ class BlockImageDiff(object):
             # zip file (plus possibly extra zeros in the last block),
             # which is what imgdiff needs to operate.  (imgdiff is
             # fine with extra zeros at the end of the file.)
-            imgdiff = (xf.intact and
+            imgdiff = (not self.disable_imgdiff and xf.intact and
                        xf.tgt_name.split(".")[-1].lower()
                        in ("apk", "jar", "zip"))
             xf.style = "imgdiff" if imgdiff else "bsdiff"
diff --git a/tools/releasetools/common.py b/tools/releasetools/common.py
index 8a5eb8961a..8d9e855713 100644
--- a/tools/releasetools/common.py
+++ b/tools/releasetools/common.py
@@ -1392,11 +1392,12 @@ def ComputeDifferences(diffs):
 
 class BlockDifference(object):
   def __init__(self, partition, tgt, src=None, check_first_block=False,
-               version=None):
+               version=None, disable_imgdiff=False):
     self.tgt = tgt
     self.src = src
     self.partition = partition
     self.check_first_block = check_first_block
+    self.disable_imgdiff = disable_imgdiff
 
     if version is None:
       version = 1
@@ -1407,7 +1408,8 @@ class BlockDifference(object):
     self.version = version
 
     b = blockimgdiff.BlockImageDiff(tgt, src, threads=OPTIONS.worker_threads,
-                                    version=self.version)
+                                    version=self.version,
+                                    disable_imgdiff=self.disable_imgdiff)
     tmpdir = tempfile.mkdtemp()
     OPTIONS.tempfiles.append(tmpdir)
     self.path = os.path.join(tmpdir, partition)
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index 69669641f0..f6db56fa1a 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -862,13 +862,21 @@ def WriteBlockIncrementalOTAPackage(target_zip, source_zip, output_zip):
         int(i) for i in
         OPTIONS.info_dict.get("blockimgdiff_versions", "1").split(","))
 
-  # Check first block of system partition for remount R/W only if
-  # disk type is ext4
-  system_partition = OPTIONS.source_info_dict["fstab"]["/system"]
-  check_first_block = system_partition.fs_type == "ext4"
+  # Check the first block of the source system partition for remount R/W only
+  # if the filesystem is ext4.
+  system_src_partition = OPTIONS.source_info_dict["fstab"]["/system"]
+  check_first_block = system_src_partition.fs_type == "ext4"
+  # Disable using imgdiff for squashfs. 'imgdiff -z' expects input files to be
+  # in zip formats. However with squashfs, a) all files are compressed in LZ4;
+  # b) the blocks listed in block map may not contain all the bytes for a given
+  # file (because they're rounded to be 4K-aligned).
+  system_tgt_partition = OPTIONS.target_info_dict["fstab"]["/system"]
+  disable_imgdiff = (system_src_partition.fs_type == "squashfs" or
+                     system_tgt_partition.fs_type == "squashfs")
   system_diff = common.BlockDifference("system", system_tgt, system_src,
                                        check_first_block,
-                                       version=blockimgdiff_version)
+                                       version=blockimgdiff_version,
+                                       disable_imgdiff=disable_imgdiff)
 
   if HasVendorPartition(target_zip):
     if not HasVendorPartition(source_zip):
@@ -882,9 +890,11 @@ def WriteBlockIncrementalOTAPackage(target_zip, source_zip, output_zip):
     # disk type is ext4
     vendor_partition = OPTIONS.source_info_dict["fstab"]["/vendor"]
     check_first_block = vendor_partition.fs_type == "ext4"
+    disable_imgdiff = vendor_partition.fs_type == "squashfs"
     vendor_diff = common.BlockDifference("vendor", vendor_tgt, vendor_src,
                                          check_first_block,
-                                         version=blockimgdiff_version)
+                                         version=blockimgdiff_version,
+                                         disable_imgdiff=disable_imgdiff)
   else:
     vendor_diff = None