diff --git a/cache.h b/cache.h
index 72410b85d7..0c245d4f10 100644
--- a/cache.h
+++ b/cache.h
@@ -1745,6 +1745,8 @@ extern const char *git_mailmap_blob;
 void maybe_flush_or_die(FILE *, const char *);
 __attribute__((format (printf, 2, 3)))
 void fprintf_or_die(FILE *, const char *fmt, ...);
+void fwrite_or_die(FILE *f, const void *buf, size_t count);
+void fflush_or_die(FILE *f);
 
 #define COPY_READ_ERROR (-2)
 #define COPY_WRITE_ERROR (-3)
diff --git a/ls-refs.c b/ls-refs.c
index 84021416ca..5ad521c6c7 100644
--- a/ls-refs.c
+++ b/ls-refs.c
@@ -107,7 +107,7 @@ static int send_ref(const char *refname, const struct object_id *oid,
 	}
 
 	strbuf_addch(&data->buf, '\n');
-	packet_write(1, data->buf.buf, data->buf.len);
+	packet_fwrite(stdout, data->buf.buf, data->buf.len);
 
 	return 0;
 }
@@ -173,7 +173,7 @@ int ls_refs(struct repository *r, struct strvec *keys,
 		strvec_push(&data.prefixes, "");
 	for_each_fullref_in_prefixes(get_git_namespace(), data.prefixes.v,
 				     send_ref, &data, 0);
-	packet_flush(1);
+	packet_fflush(stdout);
 	strvec_clear(&data.prefixes);
 	strbuf_release(&data.buf);
 	return 0;
diff --git a/pkt-line.c b/pkt-line.c
index 9f63eae2e6..de4a94b437 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -243,6 +243,43 @@ void packet_write(int fd_out, const char *buf, size_t size)
 		die("%s", err.buf);
 }
 
+void packet_fwrite(FILE *f, const char *buf, size_t size)
+{
+	size_t packet_size;
+	char header[4];
+
+	if (size > LARGE_PACKET_DATA_MAX)
+		die(_("packet write failed - data exceeds max packet size"));
+
+	packet_trace(buf, size, 1);
+	packet_size = size + 4;
+
+	set_packet_header(header, packet_size);
+	fwrite_or_die(f, header, 4);
+	fwrite_or_die(f, buf, size);
+}
+
+void packet_fwrite_fmt(FILE *fh, const char *fmt, ...)
+{
+       static struct strbuf buf = STRBUF_INIT;
+       va_list args;
+
+       strbuf_reset(&buf);
+
+       va_start(args, fmt);
+       format_packet(&buf, "", fmt, args);
+       va_end(args);
+
+       fwrite_or_die(fh, buf.buf, buf.len);
+}
+
+void packet_fflush(FILE *f)
+{
+	packet_trace("0000", 4, 1);
+	fwrite_or_die(f, "0000", 4);
+	fflush_or_die(f);
+}
+
 void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
 {
 	va_list args;
diff --git a/pkt-line.h b/pkt-line.h
index 5af5f45687..82b95e4bdd 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -35,6 +35,17 @@ int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format
 int write_packetized_from_fd_no_flush(int fd_in, int fd_out);
 int write_packetized_from_buf_no_flush(const char *src_in, size_t len, int fd_out);
 
+/*
+ * Stdio versions of packet_write functions. When mixing these with fd
+ * based functions, take care to call fflush(3) before doing fd writes or
+ * closing the fd.
+ */
+void packet_fwrite(FILE *f, const char *buf, size_t size);
+void packet_fwrite_fmt(FILE *f, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
+
+/* packet_fflush writes a flush packet and flushes the stdio buffer of f */
+void packet_fflush(FILE *f);
+
 /*
  * Read a packetized line into the buffer, which must be at least size bytes
  * long. The return value specifies the number of bytes read into the buffer.
diff --git a/upload-pack.c b/upload-pack.c
index 6ce07231d3..8ad5ee9bfc 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -1207,7 +1207,7 @@ static int send_ref(const char *refname, const struct object_id *oid,
 
 		format_symref_info(&symref_info, &data->symref);
 		format_session_id(&session_id, data);
-		packet_write_fmt(1, "%s %s%c%s%s%s%s%s%s%s object-format=%s agent=%s\n",
+		packet_fwrite_fmt(stdout, "%s %s%c%s%s%s%s%s%s%s object-format=%s agent=%s\n",
 			     oid_to_hex(oid), refname_nons,
 			     0, capabilities,
 			     (data->allow_uor & ALLOW_TIP_SHA1) ?
@@ -1223,11 +1223,11 @@ static int send_ref(const char *refname, const struct object_id *oid,
 		strbuf_release(&symref_info);
 		strbuf_release(&session_id);
 	} else {
-		packet_write_fmt(1, "%s %s\n", oid_to_hex(oid), refname_nons);
+		packet_fwrite_fmt(stdout, "%s %s\n", oid_to_hex(oid), refname_nons);
 	}
 	capabilities = NULL;
 	if (!peel_iterated_oid(oid, &peeled))
-		packet_write_fmt(1, "%s %s^{}\n", oid_to_hex(&peeled), refname_nons);
+		packet_fwrite_fmt(stdout, "%s %s^{}\n", oid_to_hex(&peeled), refname_nons);
 	return 0;
 }
 
@@ -1348,6 +1348,11 @@ void upload_pack(struct upload_pack_options *options)
 		reset_timeout(data.timeout);
 		head_ref_namespaced(send_ref, &data);
 		for_each_namespaced_ref(send_ref, &data);
+		/*
+		 * fflush stdout before calling advertise_shallow_grafts because send_ref
+		 * uses stdio.
+		 */
+		fflush_or_die(stdout);
 		advertise_shallow_grafts(1);
 		packet_flush(1);
 	} else {
diff --git a/write-or-die.c b/write-or-die.c
index d33e68f6ab..0b1ec8190b 100644
--- a/write-or-die.c
+++ b/write-or-die.c
@@ -70,3 +70,15 @@ void write_or_die(int fd, const void *buf, size_t count)
 		die_errno("write error");
 	}
 }
+
+void fwrite_or_die(FILE *f, const void *buf, size_t count)
+{
+	if (fwrite(buf, 1, count, f) != count)
+		die_errno("fwrite error");
+}
+
+void fflush_or_die(FILE *f)
+{
+	if (fflush(f))
+		die_errno("fflush error");
+}