diff --git a/libsparse/backed_block.cpp b/libsparse/backed_block.cpp
index f3d8022..6229e7c 100644
--- a/libsparse/backed_block.cpp
+++ b/libsparse/backed_block.cpp
@@ -25,7 +25,7 @@
 
 struct backed_block {
   unsigned int block;
-  unsigned int len;
+  uint64_t len;
   enum backed_block_type type;
   union {
     struct {
@@ -60,7 +60,7 @@
   return bb->next;
 }
 
-unsigned int backed_block_len(struct backed_block* bb) {
+uint64_t backed_block_len(struct backed_block* bb) {
   return bb->len;
 }
 
@@ -270,7 +270,7 @@
 }
 
 /* Queues a fill block of memory to be written to the specified data blocks */
-int backed_block_add_fill(struct backed_block_list* bbl, unsigned int fill_val, unsigned int len,
+int backed_block_add_fill(struct backed_block_list* bbl, unsigned int fill_val, uint64_t len,
                           unsigned int block) {
   struct backed_block* bb = reinterpret_cast<backed_block*>(calloc(1, sizeof(struct backed_block)));
   if (bb == nullptr) {
@@ -287,7 +287,7 @@
 }
 
 /* Queues a block of memory to be written to the specified data blocks */
-int backed_block_add_data(struct backed_block_list* bbl, void* data, unsigned int len,
+int backed_block_add_data(struct backed_block_list* bbl, void* data, uint64_t len,
                           unsigned int block) {
   struct backed_block* bb = reinterpret_cast<backed_block*>(calloc(1, sizeof(struct backed_block)));
   if (bb == nullptr) {
@@ -305,7 +305,7 @@
 
 /* Queues a chunk of a file on disk to be written to the specified data blocks */
 int backed_block_add_file(struct backed_block_list* bbl, const char* filename, int64_t offset,
-                          unsigned int len, unsigned int block) {
+                          uint64_t len, unsigned int block) {
   struct backed_block* bb = reinterpret_cast<backed_block*>(calloc(1, sizeof(struct backed_block)));
   if (bb == nullptr) {
     return -ENOMEM;
@@ -322,7 +322,7 @@
 }
 
 /* Queues a chunk of a fd to be written to the specified data blocks */
-int backed_block_add_fd(struct backed_block_list* bbl, int fd, int64_t offset, unsigned int len,
+int backed_block_add_fd(struct backed_block_list* bbl, int fd, int64_t offset, uint64_t len,
                         unsigned int block) {
   struct backed_block* bb = reinterpret_cast<backed_block*>(calloc(1, sizeof(struct backed_block)));
   if (bb == nullptr) {
diff --git a/libsparse/backed_block.h b/libsparse/backed_block.h
index 3a75460..71a8969 100644
--- a/libsparse/backed_block.h
+++ b/libsparse/backed_block.h
@@ -29,18 +29,18 @@
   BACKED_BLOCK_FILL,
 };
 
-int backed_block_add_data(struct backed_block_list* bbl, void* data, unsigned int len,
+int backed_block_add_data(struct backed_block_list* bbl, void* data, uint64_t len,
                           unsigned int block);
-int backed_block_add_fill(struct backed_block_list* bbl, unsigned int fill_val, unsigned int len,
+int backed_block_add_fill(struct backed_block_list* bbl, unsigned int fill_val, uint64_t len,
                           unsigned int block);
 int backed_block_add_file(struct backed_block_list* bbl, const char* filename, int64_t offset,
-                          unsigned int len, unsigned int block);
-int backed_block_add_fd(struct backed_block_list* bbl, int fd, int64_t offset, unsigned int len,
+                          uint64_t len, unsigned int block);
+int backed_block_add_fd(struct backed_block_list* bbl, int fd, int64_t offset, uint64_t len,
                         unsigned int block);
 
 struct backed_block* backed_block_iter_new(struct backed_block_list* bbl);
 struct backed_block* backed_block_iter_next(struct backed_block* bb);
-unsigned int backed_block_len(struct backed_block* bb);
+uint64_t backed_block_len(struct backed_block* bb);
 unsigned int backed_block_block(struct backed_block* bb);
 void* backed_block_data(struct backed_block* bb);
 const char* backed_block_filename(struct backed_block* bb);
diff --git a/libsparse/include/sparse/sparse.h b/libsparse/include/sparse/sparse.h
index 3d5fb0c..2f75349 100644
--- a/libsparse/include/sparse/sparse.h
+++ b/libsparse/include/sparse/sparse.h
@@ -75,8 +75,7 @@
  *
  * Returns 0 on success, negative errno on error.
  */
-int sparse_file_add_data(struct sparse_file *s,
-		void *data, unsigned int len, unsigned int block);
+int sparse_file_add_data(struct sparse_file* s, void* data, uint64_t len, unsigned int block);
 
 /**
  * sparse_file_add_fill - associate a fill chunk with a sparse file
@@ -93,8 +92,8 @@
  *
  * Returns 0 on success, negative errno on error.
  */
-int sparse_file_add_fill(struct sparse_file *s,
-		uint32_t fill_val, unsigned int len, unsigned int block);
+int sparse_file_add_fill(struct sparse_file* s, uint32_t fill_val, uint64_t len,
+                         unsigned int block);
 
 /**
  * sparse_file_add_file - associate a chunk of a file with a sparse file
@@ -116,9 +115,8 @@
  *
  * Returns 0 on success, negative errno on error.
  */
-int sparse_file_add_file(struct sparse_file *s,
-		const char *filename, int64_t file_offset, unsigned int len,
-		unsigned int block);
+int sparse_file_add_file(struct sparse_file* s, const char* filename, int64_t file_offset,
+                         uint64_t len, unsigned int block);
 
 /**
  * sparse_file_add_file - associate a chunk of a file with a sparse file
@@ -143,8 +141,8 @@
  *
  * Returns 0 on success, negative errno on error.
  */
-int sparse_file_add_fd(struct sparse_file *s,
-		int fd, int64_t file_offset, unsigned int len, unsigned int block);
+int sparse_file_add_fd(struct sparse_file* s, int fd, int64_t file_offset, uint64_t len,
+                       unsigned int block);
 
 /**
  * sparse_file_write - write a sparse file to a file
diff --git a/libsparse/output_file.cpp b/libsparse/output_file.cpp
index b883c13..b2c5407 100644
--- a/libsparse/output_file.cpp
+++ b/libsparse/output_file.cpp
@@ -65,9 +65,9 @@
 };
 
 struct sparse_file_ops {
-  int (*write_data_chunk)(struct output_file* out, unsigned int len, void* data);
-  int (*write_fill_chunk)(struct output_file* out, unsigned int len, uint32_t fill_val);
-  int (*write_skip_chunk)(struct output_file* out, int64_t len);
+  int (*write_data_chunk)(struct output_file* out, uint64_t len, void* data);
+  int (*write_fill_chunk)(struct output_file* out, uint64_t len, uint32_t fill_val);
+  int (*write_skip_chunk)(struct output_file* out, uint64_t len);
   int (*write_end_chunk)(struct output_file* out);
 };
 
@@ -316,7 +316,7 @@
   return 0;
 }
 
-static int write_sparse_skip_chunk(struct output_file* out, int64_t skip_len) {
+static int write_sparse_skip_chunk(struct output_file* out, uint64_t skip_len) {
   chunk_header_t chunk_header;
   int ret;
 
@@ -340,9 +340,10 @@
   return 0;
 }
 
-static int write_sparse_fill_chunk(struct output_file* out, unsigned int len, uint32_t fill_val) {
+static int write_sparse_fill_chunk(struct output_file* out, uint64_t len, uint32_t fill_val) {
   chunk_header_t chunk_header;
-  int rnd_up_len, count;
+  uint64_t rnd_up_len;
+  int count;
   int ret;
 
   /* Round up the fill length to a multiple of the block size */
@@ -370,9 +371,9 @@
   return 0;
 }
 
-static int write_sparse_data_chunk(struct output_file* out, unsigned int len, void* data) {
+static int write_sparse_data_chunk(struct output_file* out, uint64_t len, void* data) {
   chunk_header_t chunk_header;
-  int rnd_up_len, zero_len;
+  uint64_t rnd_up_len, zero_len;
   int ret;
 
   /* Round up the data length to a multiple of the block size */
@@ -437,9 +438,9 @@
     .write_end_chunk = write_sparse_end_chunk,
 };
 
-static int write_normal_data_chunk(struct output_file* out, unsigned int len, void* data) {
+static int write_normal_data_chunk(struct output_file* out, uint64_t len, void* data) {
   int ret;
-  unsigned int rnd_up_len = ALIGN(len, out->block_size);
+  uint64_t rnd_up_len = ALIGN(len, out->block_size);
 
   ret = out->ops->write(out, data, len);
   if (ret < 0) {
@@ -453,10 +454,10 @@
   return ret;
 }
 
-static int write_normal_fill_chunk(struct output_file* out, unsigned int len, uint32_t fill_val) {
+static int write_normal_fill_chunk(struct output_file* out, uint64_t len, uint32_t fill_val) {
   int ret;
   unsigned int i;
-  unsigned int write_len;
+  uint64_t write_len;
 
   /* Initialize fill_buf with the fill_val */
   for (i = 0; i < out->block_size / sizeof(uint32_t); i++) {
@@ -464,7 +465,7 @@
   }
 
   while (len) {
-    write_len = std::min(len, out->block_size);
+    write_len = std::min(len, (uint64_t)out->block_size);
     ret = out->ops->write(out, out->fill_buf, write_len);
     if (ret < 0) {
       return ret;
@@ -476,7 +477,7 @@
   return 0;
 }
 
-static int write_normal_skip_chunk(struct output_file* out, int64_t len) {
+static int write_normal_skip_chunk(struct output_file* out, uint64_t len) {
   return out->ops->skip(out, len);
 }
 
@@ -639,16 +640,16 @@
 }
 
 /* Write a contiguous region of data blocks from a memory buffer */
-int write_data_chunk(struct output_file* out, unsigned int len, void* data) {
+int write_data_chunk(struct output_file* out, uint64_t len, void* data) {
   return out->sparse_ops->write_data_chunk(out, len, data);
 }
 
 /* Write a contiguous region of data blocks with a fill value */
-int write_fill_chunk(struct output_file* out, unsigned int len, uint32_t fill_val) {
+int write_fill_chunk(struct output_file* out, uint64_t len, uint32_t fill_val) {
   return out->sparse_ops->write_fill_chunk(out, len, fill_val);
 }
 
-int write_fd_chunk(struct output_file* out, unsigned int len, int fd, int64_t offset) {
+int write_fd_chunk(struct output_file* out, uint64_t len, int fd, int64_t offset) {
   auto m = android::base::MappedFile::FromFd(fd, offset, len, PROT_READ);
   if (!m) return -errno;
 
@@ -656,7 +657,7 @@
 }
 
 /* Write a contiguous region of data blocks from a file */
-int write_file_chunk(struct output_file* out, unsigned int len, const char* file, int64_t offset) {
+int write_file_chunk(struct output_file* out, uint64_t len, const char* file, int64_t offset) {
   int ret;
 
   int file_fd = open(file, O_RDONLY | O_BINARY);
@@ -671,6 +672,6 @@
   return ret;
 }
 
-int write_skip_chunk(struct output_file* out, int64_t len) {
+int write_skip_chunk(struct output_file* out, uint64_t len) {
   return out->sparse_ops->write_skip_chunk(out, len);
 }
diff --git a/libsparse/output_file.h b/libsparse/output_file.h
index 278430b..ecbcdf3 100644
--- a/libsparse/output_file.h
+++ b/libsparse/output_file.h
@@ -30,11 +30,11 @@
 struct output_file* output_file_open_callback(int (*write)(void*, const void*, size_t), void* priv,
                                               unsigned int block_size, int64_t len, int gz,
                                               int sparse, int chunks, int crc);
-int write_data_chunk(struct output_file* out, unsigned int len, void* data);
-int write_fill_chunk(struct output_file* out, unsigned int len, uint32_t fill_val);
-int write_file_chunk(struct output_file* out, unsigned int len, const char* file, int64_t offset);
-int write_fd_chunk(struct output_file* out, unsigned int len, int fd, int64_t offset);
-int write_skip_chunk(struct output_file* out, int64_t len);
+int write_data_chunk(struct output_file* out, uint64_t len, void* data);
+int write_fill_chunk(struct output_file* out, uint64_t len, uint32_t fill_val);
+int write_file_chunk(struct output_file* out, uint64_t len, const char* file, int64_t offset);
+int write_fd_chunk(struct output_file* out, uint64_t len, int fd, int64_t offset);
+int write_skip_chunk(struct output_file* out, uint64_t len);
 void output_file_close(struct output_file* out);
 
 int read_all(int fd, void* buf, size_t len);
diff --git a/libsparse/sparse.cpp b/libsparse/sparse.cpp
index 8622b4c..396e7eb 100644
--- a/libsparse/sparse.cpp
+++ b/libsparse/sparse.cpp
@@ -50,21 +50,21 @@
   free(s);
 }
 
-int sparse_file_add_data(struct sparse_file* s, void* data, unsigned int len, unsigned int block) {
+int sparse_file_add_data(struct sparse_file* s, void* data, uint64_t len, unsigned int block) {
   return backed_block_add_data(s->backed_block_list, data, len, block);
 }
 
-int sparse_file_add_fill(struct sparse_file* s, uint32_t fill_val, unsigned int len,
+int sparse_file_add_fill(struct sparse_file* s, uint32_t fill_val, uint64_t len,
                          unsigned int block) {
   return backed_block_add_fill(s->backed_block_list, fill_val, len, block);
 }
 
 int sparse_file_add_file(struct sparse_file* s, const char* filename, int64_t file_offset,
-                         unsigned int len, unsigned int block) {
+                         uint64_t len, unsigned int block) {
   return backed_block_add_file(s->backed_block_list, filename, file_offset, len, block);
 }
 
-int sparse_file_add_fd(struct sparse_file* s, int fd, int64_t file_offset, unsigned int len,
+int sparse_file_add_fd(struct sparse_file* s, int fd, int64_t file_offset, uint64_t len,
                        unsigned int block) {
   return backed_block_add_fd(s->backed_block_list, fd, file_offset, len, block);
 }