diff --git a/libsparse/defs.h b/libsparse/defs.h
new file mode 100644
index 0000000..34e63c5
--- /dev/null
+++ b/libsparse/defs.h
@@ -0,0 +1,23 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+#ifndef _LIBSPARSE_DEFS_H_
+
+#ifndef __unused
+#define __unused        __attribute__((__unused__))
+#endif
+
+#endif /* _LIBSPARSE_DEFS_H_ */
diff --git a/libsparse/output_file.c b/libsparse/output_file.c
index e63c4a9..1cf8d8d 100644
--- a/libsparse/output_file.c
+++ b/libsparse/output_file.c
@@ -29,6 +29,7 @@
 #include <unistd.h>
 #include <zlib.h>
 
+#include "defs.h"
 #include "output_file.h"
 #include "sparse_format.h"
 #include "sparse_crc32.h"
@@ -264,7 +265,7 @@
 	.close = gz_file_close,
 };
 
-static int callback_file_open(struct output_file *out, int fd)
+static int callback_file_open(struct output_file *out __unused, int fd __unused)
 {
 	return 0;
 }
@@ -287,7 +288,7 @@
 	return 0;
 }
 
-static int callback_file_pad(struct output_file *out, int64_t len)
+static int callback_file_pad(struct output_file *out __unused, int64_t len __unused)
 {
 	return -1;
 }
@@ -631,8 +632,8 @@
 }
 
 struct output_file *output_file_open_callback(int (*write)(void *, const void *, int),
-		void *priv, unsigned int block_size, int64_t len, int gz, int sparse,
-		int chunks, int crc)
+		void *priv, unsigned int block_size, int64_t len,
+		int gz __unused, int sparse, int chunks, int crc)
 {
 	int ret;
 	struct output_file_callback *outc;
diff --git a/libsparse/sparse.c b/libsparse/sparse.c
index 741e8c6..0f107b0 100644
--- a/libsparse/sparse.c
+++ b/libsparse/sparse.c
@@ -19,6 +19,7 @@
 
 #include <sparse/sparse.h>
 
+#include "defs.h"
 #include "sparse_file.h"
 
 #include "output_file.h"
@@ -189,7 +190,7 @@
 	return ret;
 }
 
-static int out_counter_write(void *priv, const void *data, int len)
+static int out_counter_write(void *priv, const void *data __unused, int len)
 {
 	int64_t *count = priv;
 	*count += len;
diff --git a/libsparse/sparse_read.c b/libsparse/sparse_read.c
index 704bcfa..873c87c 100644
--- a/libsparse/sparse_read.c
+++ b/libsparse/sparse_read.c
@@ -29,6 +29,8 @@
 
 #include <sparse/sparse.h>
 
+#include "defs.h"
+#include "output_file.h"
 #include "sparse_crc32.h"
 #include "sparse_file.h"
 #include "sparse_format.h"
@@ -175,7 +177,8 @@
 }
 
 static int process_skip_chunk(struct sparse_file *s, unsigned int chunk_size,
-		int fd, unsigned int blocks, unsigned int block, uint32_t *crc32)
+		int fd __unused, unsigned int blocks,
+		unsigned int block __unused, uint32_t *crc32)
 {
 	int ret;
 	int chunk;