diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 7016b28485..5e8162dedf 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -288,12 +288,12 @@ static void copy_pack_data(struct hashfile *f,
 		off_t len)
 {
 	unsigned char *in;
-	unsigned long avail;
+	size_t avail;
 
 	while (len) {
 		in = use_pack(p, w_curs, offset, &avail);
 		if (avail > len)
-			avail = (unsigned long)len;
+			avail = xsize_t(len);
 		hashwrite(f, in, avail);
 		offset += avail;
 		len -= avail;
@@ -1714,8 +1714,8 @@ static void check_object(struct object_entry *entry)
 		int have_base = 0;
 		struct object_id base_ref;
 		struct object_entry *base_entry;
-		unsigned long used, used_0;
-		unsigned long avail;
+		size_t used, used_0;
+		size_t avail;
 		off_t ofs;
 		unsigned char *buf, c;
 		enum object_type type;
@@ -2176,7 +2176,8 @@ unsigned long oe_get_size_slow(struct packing_data *pack,
 	struct pack_window *w_curs;
 	unsigned char *buf;
 	enum object_type type;
-	unsigned long used, avail, size;
+	unsigned long used, size;
+	size_t avail;
 
 	if (e->type_ != OBJ_OFS_DELTA && e->type_ != OBJ_REF_DELTA) {
 		packing_data_lock(&to_pack);
diff --git a/cache.h b/cache.h
index e5885cc9ea..08795c35ba 100644
--- a/cache.h
+++ b/cache.h
@@ -21,10 +21,10 @@
 #include <zlib.h>
 typedef struct git_zstream {
 	z_stream z;
-	unsigned long avail_in;
-	unsigned long avail_out;
-	unsigned long total_in;
-	unsigned long total_out;
+	size_t avail_in;
+	size_t avail_out;
+	size_t total_in;
+	size_t total_out;
 	unsigned char *next_in;
 	unsigned char *next_out;
 } git_zstream;
@@ -41,7 +41,7 @@ void git_deflate_end(git_zstream *);
 int git_deflate_abort(git_zstream *);
 int git_deflate_end_gently(git_zstream *);
 int git_deflate(git_zstream *, int flush);
-unsigned long git_deflate_bound(git_zstream *, unsigned long);
+size_t git_deflate_bound(git_zstream *, size_t);
 
 #if defined(DT_UNKNOWN) && !defined(NO_D_TYPE_IN_DIRENT)
 #define DTYPE(de)	((de)->d_type)
diff --git a/pack-check.c b/pack-check.c
index dad6d8ae7f..1136bc2ef1 100644
--- a/pack-check.c
+++ b/pack-check.c
@@ -29,7 +29,7 @@ int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
 	uint32_t data_crc = crc32(0, NULL, 0);
 
 	do {
-		unsigned long avail;
+		size_t avail;
 		void *data = use_pack(p, w_curs, offset, &avail);
 		if (avail > len)
 			avail = len;
@@ -65,7 +65,7 @@ static int verify_packfile(struct repository *r,
 
 	r->hash_algo->init_fn(&ctx);
 	do {
-		unsigned long remaining;
+		size_t remaining;
 		unsigned char *in = use_pack(p, w_curs, offset, &remaining);
 		offset += remaining;
 		if (!pack_sig_ofs)
diff --git a/packfile.c b/packfile.c
index 6ab5233613..d30f78b4a3 100644
--- a/packfile.c
+++ b/packfile.c
@@ -613,7 +613,7 @@ static int in_window(struct pack_window *win, off_t offset)
 unsigned char *use_pack(struct packed_git *p,
 		struct pack_window **w_cursor,
 		off_t offset,
-		unsigned long *left)
+		size_t *left)
 {
 	struct pack_window *win = *w_cursor;
 
@@ -1133,7 +1133,7 @@ int unpack_object_header(struct packed_git *p,
 			 unsigned long *sizep)
 {
 	unsigned char *base;
-	unsigned long left;
+	size_t left;
 	unsigned long used;
 	enum object_type type;
 
diff --git a/packfile.h b/packfile.h
index 240aa73b95..0ba8ead4cc 100644
--- a/packfile.h
+++ b/packfile.h
@@ -87,7 +87,7 @@ int close_pack_fd(struct packed_git *p);
 
 uint32_t get_pack_fanout(struct packed_git *p, uint32_t value);
 
-unsigned char *use_pack(struct packed_git *, struct pack_window **, off_t, unsigned long *);
+unsigned char *use_pack(struct packed_git *, struct pack_window **, off_t, size_t *);
 void close_pack_windows(struct packed_git *);
 void close_pack(struct packed_git *);
 void close_object_store(struct raw_object_store *o);
diff --git a/zlib.c b/zlib.c
index d594cba3fc..197a1acc7b 100644
--- a/zlib.c
+++ b/zlib.c
@@ -29,7 +29,7 @@ static const char *zerr_to_string(int status)
  */
 /* #define ZLIB_BUF_MAX ((uInt)-1) */
 #define ZLIB_BUF_MAX ((uInt) 1024 * 1024 * 1024) /* 1GB */
-static inline uInt zlib_buf_cap(unsigned long len)
+static inline uInt zlib_buf_cap(size_t len)
 {
 	return (ZLIB_BUF_MAX < len) ? ZLIB_BUF_MAX : len;
 }
@@ -46,8 +46,8 @@ static void zlib_pre_call(git_zstream *s)
 
 static void zlib_post_call(git_zstream *s)
 {
-	unsigned long bytes_consumed;
-	unsigned long bytes_produced;
+	size_t bytes_consumed;
+	size_t bytes_produced;
 
 	bytes_consumed = s->z.next_in - s->next_in;
 	bytes_produced = s->z.next_out - s->next_out;
@@ -150,7 +150,7 @@ int git_inflate(git_zstream *strm, int flush)
 #define deflateBound(c,s)  ((s) + (((s) + 7) >> 3) + (((s) + 63) >> 6) + 11)
 #endif
 
-unsigned long git_deflate_bound(git_zstream *strm, unsigned long size)
+size_t git_deflate_bound(git_zstream *strm, size_t size)
 {
 	return deflateBound(&strm->z, size);
 }