diff --git a/attr.c b/attr.c
index c61472a4e6..b9852d8587 100644
--- a/attr.c
+++ b/attr.c
@@ -793,7 +793,7 @@ static struct attr_stack *read_attr_from_index(struct index_state *istate,
 {
 	struct attr_stack *stack = NULL;
 	char *buf;
-	unsigned long size;
+	size_t size;
 	int sparse_dir_pos = -1;
 
 	if (!istate)
diff --git a/blame.c b/blame.c
index 126e232416..6cdeabd633 100644
--- a/blame.c
+++ b/blame.c
@@ -238,7 +238,7 @@ static struct commit *fake_working_tree_commit(struct repository *r,
 		struct stat st;
 		const char *read_from;
 		char *buf_ptr;
-		unsigned long buf_len;
+		size_t buf_len;
 
 		if (contents_from) {
 			if (stat(contents_from, &st) < 0)
@@ -1034,20 +1034,17 @@ static void fill_origin_blob(struct diff_options *opt,
 {
 	if (!o->file.ptr) {
 		enum object_type type;
-		unsigned long file_size;
+		size_t file_size;
 
 		(*num_read_blob)++;
 		if (opt->flags.allow_textconv &&
 		    textconv_object(opt->repo, o->path, o->mode,
 				    &o->blob_oid, 1, &file->ptr, &file_size))
 			;
-		else {
-			size_t file_size_st = 0;
+		else
 			file->ptr = odb_read_object(the_repository->objects,
 						    &o->blob_oid, &type,
-						    &file_size_st);
-			file_size = cast_size_t_to_ulong(file_size_st);
-		}
+						    &file_size);
 		file->size = file_size;
 
 		if (!file->ptr)
@@ -2864,22 +2861,20 @@ void setup_scoreboard(struct blame_scoreboard *sb,
 		sb->final_buf_size = o->file.size;
 	}
 	else {
+		size_t final_buf_size_st = 0;
 		o = get_origin(sb->final, sb->path);
 		if (fill_blob_sha1_and_mode(sb->repo, o))
 			die(_("no such path %s in %s"), sb->path, final_commit_name);
 
 		if (sb->revs->diffopt.flags.allow_textconv &&
 		    textconv_object(sb->repo, sb->path, o->mode, &o->blob_oid, 1, (char **) &sb->final_buf,
-				    &sb->final_buf_size))
+				    &final_buf_size_st))
 			;
-		else {
-			size_t final_buf_size_st = 0;
+		else
 			sb->final_buf = odb_read_object(the_repository->objects,
 							&o->blob_oid, &type,
 							&final_buf_size_st);
-			sb->final_buf_size =
-				cast_size_t_to_ulong(final_buf_size_st);
-		}
+		sb->final_buf_size = cast_size_t_to_ulong(final_buf_size_st);
 
 		if (!sb->final_buf)
 			die(_("cannot read blob %s for path %s"),
diff --git a/builtin/cat-file.c b/builtin/cat-file.c
index d6ef8414ee..912e1ef403 100644
--- a/builtin/cat-file.c
+++ b/builtin/cat-file.c
@@ -186,11 +186,9 @@ static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
 
 	case 'c':
 	{
-		unsigned long size_ul = 0;
 		int textconv_ret = textconv_object(the_repository, path,
 						   obj_context.mode, &oid, 1,
-						   &buf, &size_ul);
-		size = size_ul;
+						   &buf, &size);
 		if (textconv_ret)
 			break;
 	}
@@ -413,12 +411,9 @@ static void print_object_or_die(struct batch_options *opt, struct expand_data *d
 					    oid_to_hex(oid), data->rest);
 			} else if (opt->transform_mode == 'c') {
 				enum object_type type;
-				unsigned long size_ul = 0;
-				if (textconv_object(the_repository,
-						    data->rest, 0100644, oid,
-						    1, &contents, &size_ul))
-					size = size_ul;
-				else
+				if (!textconv_object(the_repository,
+						     data->rest, 0100644, oid,
+						     1, &contents, &size))
 					contents = odb_read_object(the_repository->objects,
 								   oid, &type, &size);
 				if (!contents)
diff --git a/builtin/log.c b/builtin/log.c
index d027ce1e0b..2f5142e888 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -584,7 +584,7 @@ static int show_blob_object(const struct object_id *oid, struct rev_info *rev, c
 	struct object_id oidc;
 	struct object_context obj_context = {0};
 	char *buf;
-	unsigned long size;
+	size_t size;
 
 	fflush(rev->diffopt.file);
 	if (!rev->diffopt.flags.textconv_set_via_cmdline ||
diff --git a/combine-diff.c b/combine-diff.c
index fb72174918..4915bf335d 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -304,7 +304,7 @@ static struct lline *coalesce_lines(struct lline *base, int *lenbase,
 
 static char *grab_blob(struct repository *r,
 		       const struct object_id *oid, unsigned int mode,
-		       unsigned long *size, struct userdiff_driver *textconv,
+		       size_t *size, struct userdiff_driver *textconv,
 		       const char *path)
 {
 	char *blob;
@@ -325,9 +325,7 @@ static char *grab_blob(struct repository *r,
 		*size = fill_textconv(r, textconv, df, &blob);
 		free_filespec(df);
 	} else {
-		size_t size_st = 0;
-		blob = odb_read_object(r->objects, oid, &type, &size_st);
-		*size = cast_size_t_to_ulong(size_st);
+		blob = odb_read_object(r->objects, oid, &type, size);
 		if (!blob)
 			die(_("unable to read %s"), oid_to_hex(oid));
 		if (type != OBJ_BLOB)
@@ -431,7 +429,7 @@ static void combine_diff(struct repository *r,
 	xdemitconf_t xecfg;
 	mmfile_t parent_file;
 	struct combine_diff_state state;
-	unsigned long sz;
+	size_t sz;
 
 	if (result_deleted)
 		return; /* result deleted */
@@ -1015,7 +1013,7 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 			    struct rev_info *rev)
 {
 	struct diff_options *opt = &rev->diffopt;
-	unsigned long result_size, cnt, lno;
+	size_t result_size, cnt, lno;
 	int result_deleted = 0;
 	char *result, *cp;
 	struct sline *sline; /* survived lines */
@@ -1134,7 +1132,7 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 		is_binary = buffer_is_binary(result, result_size);
 		for (i = 0; !is_binary && i < num_parent; i++) {
 			char *buf;
-			unsigned long size;
+			size_t size;
 			buf = grab_blob(opt->repo,
 					&elem->parent[i].oid,
 					elem->parent[i].mode,
diff --git a/convert.c b/convert.c
index 036506842c..77f06fcfdb 100644
--- a/convert.c
+++ b/convert.c
@@ -102,7 +102,7 @@ static int convert_is_binary(const struct text_stat *stats)
 	return 0;
 }
 
-static unsigned int gather_convert_stats(const char *data, unsigned long size)
+static unsigned int gather_convert_stats(const char *data, size_t size)
 {
 	struct text_stat stats;
 	int ret = 0;
@@ -119,7 +119,7 @@ static unsigned int gather_convert_stats(const char *data, unsigned long size)
 	return ret;
 }
 
-static const char *gather_convert_stats_ascii(const char *data, unsigned long size)
+static const char *gather_convert_stats_ascii(const char *data, size_t size)
 {
 	unsigned int convert_stats = gather_convert_stats(data, size);
 
@@ -141,7 +141,7 @@ const char *get_cached_convert_stats_ascii(struct index_state *istate,
 					   const char *path)
 {
 	const char *ret;
-	unsigned long sz;
+	size_t sz;
 	void *data = read_blob_data_from_index(istate, path, &sz);
 	ret = gather_convert_stats_ascii(data, sz);
 	free(data);
@@ -223,7 +223,7 @@ static void check_global_conv_flags_eol(const char *path,
 
 static int has_crlf_in_index(struct index_state *istate, const char *path)
 {
-	unsigned long sz;
+	size_t sz;
 	void *data;
 	const char *crp;
 	int has_crlf = 0;
diff --git a/diff.c b/diff.c
index c14f69719b..de5ff1f7d0 100644
--- a/diff.c
+++ b/diff.c
@@ -3606,8 +3606,8 @@ static int checkdiff_consume(void *priv, char *line, unsigned long len)
 }
 
 static unsigned char *deflate_it(char *data,
-				 unsigned long size,
-				 unsigned long *result_size)
+				 size_t size,
+				 size_t *result_size)
 {
 	size_t bound;
 	unsigned char *deflated;
@@ -3636,10 +3636,10 @@ static void emit_binary_diff_body(struct diff_options *o,
 	void *delta;
 	void *deflated;
 	void *data;
-	unsigned long orig_size;
-	unsigned long delta_size;
-	unsigned long deflate_size;
-	unsigned long data_size;
+	size_t orig_size;
+	size_t delta_size;
+	size_t deflate_size;
+	size_t data_size;
 
 	/* We could do deflated delta, or we could do just deflated two,
 	 * whichever is smaller.
@@ -3647,11 +3647,9 @@ static void emit_binary_diff_body(struct diff_options *o,
 	delta = NULL;
 	deflated = deflate_it(two->ptr, two->size, &deflate_size);
 	if (one->size && two->size) {
-		size_t delta_size_st = 0;
 		delta = diff_delta(one->ptr, one->size,
 				   two->ptr, two->size,
-				   &delta_size_st, deflate_size);
-		delta_size = cast_size_t_to_ulong(delta_size_st);
+				   &delta_size, deflate_size);
 		if (delta) {
 			void *to_free = delta;
 			orig_size = delta_size;
@@ -4597,9 +4595,8 @@ int diff_populate_filespec(struct repository *r,
 		}
 	}
 	else {
-		size_t size_st = 0;
 		struct object_info info = {
-			.sizep = &size_st
+			.sizep = &s->size
 		};
 
 		if (!(size_only || check_binary))
@@ -4621,7 +4618,6 @@ int diff_populate_filespec(struct repository *r,
 			die("unable to read %s", oid_to_hex(&s->oid));
 
 object_read:
-		s->size = cast_size_t_to_ulong(size_st);
 		if (size_only || check_binary) {
 			if (size_only)
 				return 0;
@@ -4636,7 +4632,6 @@ object_read:
 			if (odb_read_object_info_extended(r->objects, &s->oid, &info,
 							  OBJECT_INFO_LOOKUP_REPLACE))
 				die("unable to read %s", oid_to_hex(&s->oid));
-			s->size = cast_size_t_to_ulong(size_st);
 		}
 		s->should_free = 1;
 	}
@@ -7847,7 +7842,7 @@ int textconv_object(struct repository *r,
 		    const struct object_id *oid,
 		    int oid_valid,
 		    char **buf,
-		    unsigned long *buf_size)
+		    size_t *buf_size)
 {
 	struct diff_filespec *df;
 	struct userdiff_driver *textconv;
diff --git a/diff.h b/diff.h
index bb5cddaf34..ab52ca80c3 100644
--- a/diff.h
+++ b/diff.h
@@ -757,7 +757,7 @@ int textconv_object(struct repository *repo,
 		    const char *path,
 		    unsigned mode,
 		    const struct object_id *oid, int oid_valid,
-		    char **buf, unsigned long *buf_size);
+		    char **buf, size_t *buf_size);
 
 int parse_rename_score(const char **cp_p);
 
diff --git a/diffcore.h b/diffcore.h
index d75038d1b3..85fc94e2a5 100644
--- a/diffcore.h
+++ b/diffcore.h
@@ -54,7 +54,7 @@ struct diff_filespec {
 	char *path;
 	void *data;
 	void *cnt_data;
-	unsigned long size;
+	size_t size;
 	int count;               /* Reference count */
 	int rename_used;         /* Count of rename users */
 	unsigned short mode;	 /* file mode */
diff --git a/read-cache-ll.h b/read-cache-ll.h
index 2c8b4b21b1..a3643dce24 100644
--- a/read-cache-ll.h
+++ b/read-cache-ll.h
@@ -411,7 +411,7 @@ int chmod_index_entry(struct index_state *, struct cache_entry *ce, char flip);
 int ce_same_name(const struct cache_entry *a, const struct cache_entry *b);
 void set_object_name_for_intent_to_add_entry(struct cache_entry *ce);
 int index_name_is_other(struct index_state *, const char *, int);
-void *read_blob_data_from_index(struct index_state *, const char *, unsigned long *);
+void *read_blob_data_from_index(struct index_state *, const char *, size_t *);
 
 /* do stat comparison even if CE_VALID is true */
 #define CE_MATCH_IGNORE_VALID		01
diff --git a/read-cache.c b/read-cache.c
index 21ca58beea..8be8912f16 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -3459,7 +3459,7 @@ int index_name_is_other(struct index_state *istate, const char *name,
 }
 
 void *read_blob_data_from_index(struct index_state *istate,
-				const char *path, unsigned long *size)
+				const char *path, size_t *size)
 {
 	int pos, len;
 	size_t sz;
@@ -3490,7 +3490,7 @@ void *read_blob_data_from_index(struct index_state *istate,
 		return NULL;
 	}
 	if (size)
-		*size = cast_size_t_to_ulong(sz);
+		*size = sz;
 	return data;
 }
 
diff --git a/xdiff-interface.c b/xdiff-interface.c
index db6938689f..18e37d2479 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -195,7 +195,7 @@ void read_mmblob(mmfile_t *ptr, struct object_database *odb,
 }
 
 #define FIRST_FEW_BYTES 8000
-int buffer_is_binary(const char *ptr, unsigned long size)
+int buffer_is_binary(const char *ptr, size_t size)
 {
 	if (FIRST_FEW_BYTES < size)
 		size = FIRST_FEW_BYTES;
diff --git a/xdiff-interface.h b/xdiff-interface.h
index ce54e1c0e0..41fa1d7562 100644
--- a/xdiff-interface.h
+++ b/xdiff-interface.h
@@ -49,7 +49,7 @@ int xdi_diff_outf(mmfile_t *mf1, mmfile_t *mf2,
 int read_mmfile(mmfile_t *ptr, const char *filename);
 void read_mmblob(mmfile_t *ptr, struct object_database *odb,
 		 const struct object_id *oid);
-int buffer_is_binary(const char *ptr, unsigned long size);
+int buffer_is_binary(const char *ptr, size_t size);
 
 void xdiff_set_find_func(xdemitconf_t *xecfg, const char *line, int cflags);
 void xdiff_clear_find_func(xdemitconf_t *xecfg);