diff --git a/applypatch/Makefile b/applypatch/Makefile
new file mode 100644
index 0000000..fa6298d
--- /dev/null
+++ b/applypatch/Makefile
@@ -0,0 +1,32 @@
+# Copyright (C) 2016 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This file is for building imgdiff in Chrome OS.
+
+CPPFLAGS += -iquote..
+CXXFLAGS += -std=c++11 -O3 -Wall -Werror
+LDLIBS += -lbz2 -lz
+
+.PHONY: all clean
+
+all: imgdiff libimgpatch.a
+
+clean:
+	rm -f *.o imgdiff libimgpatch.a
+
+imgdiff: imgdiff.o bsdiff.o utils.o
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(LDLIBS) -o $@ $^
+
+libimgpatch.a: imgpatch.o bspatch.o utils.o
+	${AR} rcs $@ $^
diff --git a/applypatch/applypatch.h b/applypatch/applypatch.h
index 14fb490..096596f 100644
--- a/applypatch/applypatch.h
+++ b/applypatch/applypatch.h
@@ -17,6 +17,7 @@
 #ifndef _APPLYPATCH_H
 #define _APPLYPATCH_H
 
+#include <stdint.h>
 #include <sys/stat.h>
 
 #include <vector>
diff --git a/applypatch/bsdiff.cpp b/applypatch/bsdiff.cpp
index 55dbe5c..cca1b32 100644
--- a/applypatch/bsdiff.cpp
+++ b/applypatch/bsdiff.cpp
@@ -224,7 +224,6 @@
 int bsdiff(u_char* old, off_t oldsize, off_t** IP, u_char* newdata, off_t newsize,
            const char* patch_filename)
 {
-	int fd;
 	off_t *I;
 	off_t scan,pos,len;
 	off_t lastscan,lastpos,lastoffset;
diff --git a/applypatch/bspatch.cpp b/applypatch/bspatch.cpp
index ebb55f1..1fc1455 100644
--- a/applypatch/bspatch.cpp
+++ b/applypatch/bspatch.cpp
@@ -182,7 +182,6 @@
 
     off_t oldpos = 0, newpos = 0;
     off_t ctrl[3];
-    off_t len_read;
     int i;
     unsigned char buf[24];
     while (newpos < new_size) {
diff --git a/applypatch/imgdiff.cpp b/applypatch/imgdiff.cpp
index f22502e..a3c10b4 100644
--- a/applypatch/imgdiff.cpp
+++ b/applypatch/imgdiff.cpp
@@ -598,7 +598,6 @@
     return -1;
   }
 
-  size_t p = 0;
   unsigned char* out = reinterpret_cast<unsigned char*>(malloc(BUFFER_SIZE));
 
   // We only check two combinations of encoder parameters:  level 6
@@ -844,7 +843,6 @@
   }
 
   if (argc != 4) {
-    usage:
     printf("usage: %s [-z] [-b <bonus-file>] <src-img> <tgt-img> <patch-file>\n",
             argv[0]);
     return 2;
diff --git a/applypatch/imgpatch.cpp b/applypatch/imgpatch.cpp
index 8824038..0ab995b 100644
--- a/applypatch/imgpatch.cpp
+++ b/applypatch/imgpatch.cpp
@@ -130,6 +130,7 @@
             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);
@@ -195,6 +196,11 @@
                                     &uncompressed_target_data) != 0) {
                 return -1;
             }
+            if (uncompressed_target_data.size() != target_len) {
+                printf("expected target len to be %zu, but it's %zu\n",
+                       target_len, uncompressed_target_data.size());
+                return -1;
+            }
 
             // Now compress the target data and append it to the output.