diff --git a/tools/applypatch/imgpatch.c b/tools/applypatch/imgpatch.c
index 2efe874..697cc68 100644
--- a/tools/applypatch/imgpatch.c
+++ b/tools/applypatch/imgpatch.c
@@ -27,24 +27,7 @@
 #include "mincrypt/sha.h"
 #include "applypatch.h"
 #include "imgdiff.h"
-
-int Read4(unsigned char* p) {
-  return (int)(((unsigned int)p[3] << 24) |
-               ((unsigned int)p[2] << 16) |
-               ((unsigned int)p[1] << 8) |
-               (unsigned int)p[0]);
-}
-
-long long Read8(unsigned char* p) {
-  return (long long)(((unsigned long long)p[7] << 56) |
-                     ((unsigned long long)p[6] << 48) |
-                     ((unsigned long long)p[5] << 40) |
-                     ((unsigned long long)p[4] << 32) |
-                     ((unsigned long long)p[3] << 24) |
-                     ((unsigned long long)p[2] << 16) |
-                     ((unsigned long long)p[1] << 8) |
-                     (unsigned long long)p[0]);
-}
+#include "utils.h"
 
 /*
  * Apply the patch given in 'patch_filename' to the source data given
@@ -67,7 +50,10 @@
     return -1;
   }
 
-  if (memcmp(header, "IMGDIFF1", 8) != 0) {
+  // IMGDIFF1 uses CHUNK_NORMAL and CHUNK_GZIP.
+  // IMGDIFF2 uses CHUNK_NORMAL, CHUNK_DEFLATE, and CHUNK_RAW.
+  if (memcmp(header, "IMGDIFF", 7) != 0 ||
+      (header[7] != '1' && header[7] != '2')) {
     fprintf(stderr, "corrupt patch file header (magic number)\n");
     return -1;
   }
@@ -76,48 +62,67 @@
 
   int i;
   for (i = 0; i < num_chunks; ++i) {
-    // each chunk's header record starts with 28 bytes (4 + 8*3).
-    unsigned char chunk[28];
-    if (fread(chunk, 1, 28, f) != 28) {
+    // each chunk's header record starts with 4 bytes.
+    unsigned char chunk[4];
+    if (fread(chunk, 1, 4, f) != 4) {
       fprintf(stderr, "failed to read chunk %d record\n", i);
       return -1;
     }
 
     int type = Read4(chunk);
-    size_t src_start = Read8(chunk+4);
-    size_t src_len = Read8(chunk+12);
-    size_t patch_offset = Read8(chunk+20);
 
     if (type == CHUNK_NORMAL) {
+      unsigned char normal_header[24];
+      if (fread(normal_header, 1, 24, f) != 24) {
+        fprintf(stderr, "failed to read chunk %d normal header data\n", i);
+        return -1;
+      }
+
+      size_t src_start = Read8(normal_header);
+      size_t src_len = Read8(normal_header+8);
+      size_t patch_offset = Read8(normal_header+16);
+
       fprintf(stderr, "CHUNK %d:  normal   patch offset %d\n", i, patch_offset);
 
       ApplyBSDiffPatch(old_data + src_start, src_len,
                        patch_filename, patch_offset,
                        output, ctx);
     } else if (type == CHUNK_GZIP) {
-      fprintf(stderr, "CHUNK %d:  gzip     patch offset %d\n", i, patch_offset);
+      // This branch is basically a duplicate of the CHUNK_DEFLATE
+      // branch, with a bit of extra processing for the gzip header
+      // and footer.  I've avoided factoring the common code out since
+      // this branch will just be deleted when we drop support for
+      // IMGDIFF1.
 
-      // gzip chunks have an additional 40 + gzip_header_len + 8 bytes
+      // gzip chunks have an additional 64 + gzip_header_len + 8 bytes
       // in their chunk header.
-      unsigned char* gzip = malloc(40);
-      if (fread(gzip, 1, 40, f) != 40) {
-        fprintf(stderr, "failed to read chunk %d initial gzip data\n", i);
+      unsigned char* gzip = malloc(64);
+      if (fread(gzip, 1, 64, f) != 64) {
+        fprintf(stderr, "failed to read chunk %d initial gzip header data\n",
+                i);
         return -1;
       }
-      size_t gzip_header_len = Read4(gzip+36);
-      gzip = realloc(gzip, 40 + gzip_header_len + 8);
-      if (fread(gzip+40, 1, gzip_header_len+8, f) != gzip_header_len+8) {
-        fprintf(stderr, "failed to read chunk %d remaining gzip data\n", i);
+      size_t gzip_header_len = Read4(gzip+60);
+      gzip = realloc(gzip, 64 + gzip_header_len + 8);
+      if (fread(gzip+64, 1, gzip_header_len+8, f) != gzip_header_len+8) {
+        fprintf(stderr, "failed to read chunk %d remaining gzip header data\n",
+                i);
         return -1;
       }
 
-      size_t expanded_len = Read8(gzip);
-      size_t target_len = Read8(gzip);
-      int gz_level = Read4(gzip+16);
-      int gz_method = Read4(gzip+20);
-      int gz_windowBits = Read4(gzip+24);
-      int gz_memLevel = Read4(gzip+28);
-      int gz_strategy = Read4(gzip+32);
+      size_t src_start = Read8(gzip);
+      size_t src_len = Read8(gzip+8);
+      size_t patch_offset = Read8(gzip+16);
+
+      size_t expanded_len = Read8(gzip+24);
+      size_t target_len = Read8(gzip+32);
+      int gz_level = Read4(gzip+40);
+      int gz_method = Read4(gzip+44);
+      int gz_windowBits = Read4(gzip+48);
+      int gz_memLevel = Read4(gzip+52);
+      int gz_strategy = Read4(gzip+56);
+
+      fprintf(stderr, "CHUNK %d:  gzip     patch offset %d\n", i, patch_offset);
 
       // Decompress the source data; the chunk header tells us exactly
       // how big we expect it to be when decompressed.
@@ -173,8 +178,8 @@
       // Now compress the target data and append it to the output.
 
       // start with the gzip header.
-      fwrite(gzip+40, 1, gzip_header_len, output);
-      SHA_update(ctx, gzip+40, gzip_header_len);
+      fwrite(gzip+64, 1, gzip_header_len, output);
+      SHA_update(ctx, gzip+64, gzip_header_len);
 
       // we're done with the expanded_source data buffer, so we'll
       // reuse that memory to receive the output of deflate.
@@ -212,12 +217,143 @@
       deflateEnd(&strm);
 
       // lastly, the gzip footer.
-      fwrite(gzip+40+gzip_header_len, 1, 8, output);
-      SHA_update(ctx, gzip+40+gzip_header_len, 8);
+      fwrite(gzip+64+gzip_header_len, 1, 8, output);
+      SHA_update(ctx, gzip+64+gzip_header_len, 8);
 
       free(temp_data);
       free(uncompressed_target_data);
       free(gzip);
+    } else if (type == CHUNK_RAW) {
+      unsigned char raw_header[4];
+      if (fread(raw_header, 1, 4, f) != 4) {
+        fprintf(stderr, "failed to read chunk %d raw header data\n", i);
+        return -1;
+      }
+
+      size_t data_len = Read4(raw_header);
+
+      fprintf(stderr, "CHUNK %d:  raw      data %d\n", i, data_len);
+
+      unsigned char* temp = malloc(data_len);
+      if (fread(temp, 1, data_len, f) != data_len) {
+          fprintf(stderr, "failed to read chunk %d raw data\n", i);
+          return -1;
+      }
+      SHA_update(ctx, temp, data_len);
+      if (fwrite(temp, 1, data_len, output) != data_len) {
+          fprintf(stderr, "failed to write chunk %d raw data\n", i);
+          return -1;
+      }
+    } else if (type == CHUNK_DEFLATE) {
+      // deflate chunks have an additional 60 bytes in their chunk header.
+      unsigned char deflate_header[60];
+      if (fread(deflate_header, 1, 60, f) != 60) {
+        fprintf(stderr, "failed to read chunk %d deflate header data\n", i);
+        return -1;
+      }
+
+      size_t src_start = Read8(deflate_header);
+      size_t src_len = Read8(deflate_header+8);
+      size_t patch_offset = Read8(deflate_header+16);
+      size_t expanded_len = Read8(deflate_header+24);
+      size_t target_len = Read8(deflate_header+32);
+      int level = Read4(deflate_header+40);
+      int method = Read4(deflate_header+44);
+      int windowBits = Read4(deflate_header+48);
+      int memLevel = Read4(deflate_header+52);
+      int strategy = Read4(deflate_header+56);
+
+      fprintf(stderr, "CHUNK %d:  deflate  patch offset %d\n", i, patch_offset);
+
+      // Decompress the source data; the chunk header tells us exactly
+      // how big we expect it to be when decompressed.
+
+      unsigned char* expanded_source = malloc(expanded_len);
+      if (expanded_source == NULL) {
+        fprintf(stderr, "failed to allocate %d bytes for expanded_source\n",
+                expanded_len);
+        return -1;
+      }
+
+      z_stream strm;
+      strm.zalloc = Z_NULL;
+      strm.zfree = Z_NULL;
+      strm.opaque = Z_NULL;
+      strm.avail_in = src_len;
+      strm.next_in = (unsigned char*)(old_data + src_start);
+      strm.avail_out = expanded_len;
+      strm.next_out = expanded_source;
+
+      int ret;
+      ret = inflateInit2(&strm, -15);
+      if (ret != Z_OK) {
+        fprintf(stderr, "failed to init source inflation: %d\n", ret);
+        return -1;
+      }
+
+      // Because we've provided enough room to accommodate the output
+      // data, we expect one call to inflate() to suffice.
+      ret = inflate(&strm, Z_SYNC_FLUSH);
+      if (ret != Z_STREAM_END) {
+        fprintf(stderr, "source inflation returned %d\n", ret);
+        return -1;
+      }
+      // We should have filled the output buffer exactly.
+      if (strm.avail_out != 0) {
+        fprintf(stderr, "source inflation short by %d bytes\n", strm.avail_out);
+        return -1;
+      }
+      inflateEnd(&strm);
+
+      // Next, apply the bsdiff patch (in memory) to the uncompressed
+      // data.
+      unsigned char* uncompressed_target_data;
+      ssize_t uncompressed_target_size;
+      if (ApplyBSDiffPatchMem(expanded_source, expanded_len,
+                              patch_filename, patch_offset,
+                              &uncompressed_target_data,
+                              &uncompressed_target_size) != 0) {
+        return -1;
+      }
+
+      // Now compress the target data and append it to the output.
+
+      // we're done with the expanded_source data buffer, so we'll
+      // reuse that memory to receive the output of deflate.
+      unsigned char* temp_data = expanded_source;
+      ssize_t temp_size = expanded_len;
+      if (temp_size < 32768) {
+        // ... unless the buffer is too small, in which case we'll
+        // allocate a fresh one.
+        free(temp_data);
+        temp_data = malloc(32768);
+        temp_size = 32768;
+      }
+
+      // now the deflate stream
+      strm.zalloc = Z_NULL;
+      strm.zfree = Z_NULL;
+      strm.opaque = Z_NULL;
+      strm.avail_in = uncompressed_target_size;
+      strm.next_in = uncompressed_target_data;
+      ret = deflateInit2(&strm, level, method, windowBits, memLevel, strategy);
+      do {
+        strm.avail_out = temp_size;
+        strm.next_out = temp_data;
+        ret = deflate(&strm, Z_FINISH);
+        size_t have = temp_size - strm.avail_out;
+
+        if (fwrite(temp_data, 1, have, output) != have) {
+          fprintf(stderr, "failed to write %d compressed bytes to output\n",
+                  have);
+          return -1;
+        }
+        SHA_update(ctx, temp_data, have);
+      } while (ret != Z_STREAM_END);
+      deflateEnd(&strm);
+
+      free(temp_data);
+      free(uncompressed_target_data);
     } else {
       fprintf(stderr, "patch chunk %d is unknown type %d\n", i, type);
       return -1;