diff --git a/libsparse/Android.mk b/libsparse/Android.mk
index 4aba168..0abe33d 100644
--- a/libsparse/Android.mk
+++ b/libsparse/Android.mk
@@ -17,6 +17,7 @@
 LOCAL_MODULE := libsparse_host
 LOCAL_STATIC_LIBRARIES := libz
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/include external/zlib
+LOCAL_CFLAGS := -Werror
 include $(BUILD_HOST_STATIC_LIBRARY)
 
 
@@ -27,6 +28,7 @@
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/include external/zlib
 LOCAL_SHARED_LIBRARIES := \
     libz
+LOCAL_CFLAGS := -Werror
 include $(BUILD_SHARED_LIBRARY)
 
 
@@ -36,6 +38,7 @@
 LOCAL_MODULE := libsparse_static
 LOCAL_C_INCLUDES += $(LOCAL_PATH)/include external/zlib
 LOCAL_STATIC_LIBRARIES := libz
+LOCAL_CFLAGS := -Werror
 include $(BUILD_STATIC_LIBRARY)
 
 
@@ -48,6 +51,7 @@
 LOCAL_STATIC_LIBRARIES := \
     libsparse_host \
     libz
+LOCAL_CFLAGS := -Werror
 include $(BUILD_HOST_EXECUTABLE)
 
 
@@ -58,6 +62,7 @@
 LOCAL_STATIC_LIBRARIES := \
     libsparse_static \
     libz
+LOCAL_CFLAGS := -Werror
 include $(BUILD_EXECUTABLE)
 
 
@@ -69,6 +74,7 @@
 LOCAL_STATIC_LIBRARIES := \
     libsparse_host \
     libz
+LOCAL_CFLAGS := -Werror
 include $(BUILD_HOST_EXECUTABLE)
 
 
@@ -78,6 +84,7 @@
 LOCAL_STATIC_LIBRARIES := \
     libsparse_static \
     libz
+LOCAL_CFLAGS := -Werror
 include $(BUILD_EXECUTABLE)
 
 
@@ -89,6 +96,7 @@
 LOCAL_STATIC_LIBRARIES := \
     libsparse_host \
     libz
+LOCAL_CFLAGS := -Werror
 include $(BUILD_HOST_EXECUTABLE)
 
 endif
@@ -98,5 +106,5 @@
 LOCAL_SRC_FILES := simg_dump.py
 LOCAL_MODULE_CLASS := EXECUTABLES
 LOCAL_IS_HOST_MODULE := true
+LOCAL_CFLAGS := -Werror
 include $(BUILD_PREBUILT)
-
diff --git a/libsparse/img2simg.c b/libsparse/img2simg.c
index 6b1caa5..a0db36f 100644
--- a/libsparse/img2simg.c
+++ b/libsparse/img2simg.c
@@ -47,7 +47,6 @@
 {
 	int in;
 	int out;
-	unsigned int i;
 	int ret;
 	struct sparse_file *s;
 	unsigned int block_size = 4096;
diff --git a/libsparse/output_file.c b/libsparse/output_file.c
index 1cf8d8d..cd30800 100644
--- a/libsparse/output_file.c
+++ b/libsparse/output_file.c
@@ -31,8 +31,8 @@
 
 #include "defs.h"
 #include "output_file.h"
-#include "sparse_format.h"
 #include "sparse_crc32.h"
+#include "sparse_format.h"
 
 #ifndef USE_MINGW
 #include <sys/mman.h>
@@ -295,7 +295,6 @@
 
 static int callback_file_write(struct output_file *out, void *data, int len)
 {
-	int ret;
 	struct output_file_callback *outc = to_output_file_callback(out);
 
 	return outc->write(outc->priv, data, len);
@@ -341,7 +340,7 @@
 static int write_sparse_skip_chunk(struct output_file *out, int64_t skip_len)
 {
 	chunk_header_t chunk_header;
-	int ret, chunk;
+	int ret;
 
 	if (skip_len % out->block_size) {
 		error("don't care size %"PRIi64" is not a multiple of the block size %u",
@@ -368,9 +367,8 @@
 		uint32_t fill_val)
 {
 	chunk_header_t chunk_header;
-	int rnd_up_len, zero_len, count;
+	int rnd_up_len, count;
 	int ret;
-	unsigned int i;
 
 	/* Round up the fill length to a multiple of the block size */
 	rnd_up_len = ALIGN(len, out->block_size);
@@ -536,8 +534,6 @@
 
 void output_file_close(struct output_file *out)
 {
-	int ret;
-
 	out->sparse_ops->write_end_chunk(out);
 	out->ops->close(out);
 }
diff --git a/libsparse/sparse.c b/libsparse/sparse.c
index 0f107b0..baa30cd 100644
--- a/libsparse/sparse.c
+++ b/libsparse/sparse.c
@@ -279,7 +279,6 @@
 		struct sparse_file **out_s, int out_s_count)
 {
 	struct backed_block *bb;
-	unsigned int overhead;
 	struct sparse_file *s;
 	struct sparse_file *tmp;
 	int c = 0;
diff --git a/libsparse/sparse_read.c b/libsparse/sparse_read.c
index 873c87c..8e188e9 100644
--- a/libsparse/sparse_read.c
+++ b/libsparse/sparse_read.c
@@ -180,22 +180,16 @@
 		int fd __unused, unsigned int blocks,
 		unsigned int block __unused, uint32_t *crc32)
 {
-	int ret;
-	int chunk;
-	int64_t len = (int64_t)blocks * s->block_size;
-	uint32_t fill_val;
-	uint32_t *fillbuf;
-	unsigned int i;
-
 	if (chunk_size != 0) {
 		return -EINVAL;
 	}
 
 	if (crc32) {
+	        int64_t len = (int64_t)blocks * s->block_size;
 		memset(copybuf, 0, COPY_BUF_SIZE);
 
 		while (len) {
-			chunk = min(len, COPY_BUF_SIZE);
+			int chunk = min(len, COPY_BUF_SIZE);
 			*crc32 = sparse_crc32(*crc32, copybuf, chunk);
 			len -= chunk;
 		}
@@ -367,7 +361,6 @@
 	int64_t remain = s->len;
 	int64_t offset = 0;
 	unsigned int to_read;
-	char *ptr;
 	unsigned int i;
 	bool sparse_block;