diff --git a/object-file.c b/object-file.c
index 2bc36ab3ee..af24a5dc79 100644
--- a/object-file.c
+++ b/object-file.c
@@ -503,7 +503,7 @@ cleanup:
 static void hash_object_body(const struct git_hash_algo *algo, struct git_hash_ctx *c,
 			     const void *buf, unsigned long len,
 			     struct object_id *oid,
-			     char *hdr, int *hdrlen)
+			     char *hdr, size_t *hdrlen)
 {
 	algo->init_fn(c);
 	git_hash_update(c, hdr, *hdrlen);
@@ -512,9 +512,9 @@ static void hash_object_body(const struct git_hash_algo *algo, struct git_hash_c
 }
 
 static void write_object_file_prepare(const struct git_hash_algo *algo,
-				      const void *buf, unsigned long len,
+				      const void *buf, size_t len,
 				      enum object_type type, struct object_id *oid,
-				      char *hdr, int *hdrlen)
+				      char *hdr, size_t *hdrlen)
 {
 	struct git_hash_ctx c;
 
@@ -657,11 +657,11 @@ out:
 }
 
 void hash_object_file(const struct git_hash_algo *algo, const void *buf,
-		      unsigned long len, enum object_type type,
+		      size_t len, enum object_type type,
 		      struct object_id *oid)
 {
 	char hdr[MAX_HEADER_LEN];
-	int hdrlen = sizeof(hdr);
+	size_t hdrlen = sizeof(hdr);
 
 	write_object_file_prepare(algo, buf, len, type, oid, hdr, &hdrlen);
 }
@@ -1037,7 +1037,7 @@ cleanup:
 }
 
 int write_object_file(struct odb_source *source,
-		      const void *buf, unsigned long len,
+		      const void *buf, size_t len,
 		      enum object_type type, struct object_id *oid,
 		      struct object_id *compat_oid_in, unsigned flags)
 {
@@ -1045,7 +1045,7 @@ int write_object_file(struct odb_source *source,
 	const struct git_hash_algo *compat = source->odb->repo->compat_hash_algo;
 	struct object_id compat_oid;
 	char hdr[MAX_HEADER_LEN];
-	int hdrlen = sizeof(hdr);
+	size_t hdrlen = sizeof(hdr);
 
 	/* Generate compat_oid */
 	if (compat) {
diff --git a/object-file.h b/object-file.h
index 15d97630d3..dc24393a9e 100644
--- a/object-file.h
+++ b/object-file.h
@@ -147,7 +147,7 @@ struct object_info;
 int parse_loose_header(const char *hdr, struct object_info *oi);
 
 int write_object_file(struct odb_source *source,
-		      const void *buf, unsigned long len,
+		      const void *buf, size_t len,
 		      enum object_type type, struct object_id *oid,
 		      struct object_id *compat_oid_in, unsigned flags);
 
@@ -197,7 +197,7 @@ int finalize_object_file_flags(struct repository *repo,
 			       enum finalize_object_file_flags flags);
 
 void hash_object_file(const struct git_hash_algo *algo, const void *buf,
-		      unsigned long len, enum object_type type,
+		      size_t len, enum object_type type,
 		      struct object_id *oid);
 
 /* Helper to check and "touch" a file */