diff --git a/builtin/receive-pack.c b/builtin/receive-pack.c
index 2cb854f..165a633 100644
--- a/builtin/receive-pack.c
+++ b/builtin/receive-pack.c
@@ -701,7 +701,7 @@
 
 	if (unpacker_error) {
 		for (cmd = commands; cmd; cmd = cmd->next)
-			cmd->error_string = "n/a (unpacker error)";
+			cmd->error_string = "unpacker error";
 		return;
 	}
 
@@ -801,7 +801,7 @@
 
 static const char *pack_lockfile;
 
-static const char *unpack(void)
+static const char *unpack(int err_fd)
 {
 	struct pack_header hdr;
 	const char *hdr_err;
@@ -821,6 +821,7 @@
 
 	if (ntohl(hdr.hdr_entries) < unpack_limit) {
 		int code, i = 0;
+		struct child_process child;
 		const char *unpacker[5];
 		unpacker[i++] = "unpack-objects";
 		if (quiet)
@@ -829,7 +830,12 @@
 			unpacker[i++] = "--strict";
 		unpacker[i++] = hdr_arg;
 		unpacker[i++] = NULL;
-		code = run_command_v_opt(unpacker, RUN_GIT_CMD);
+		memset(&child, 0, sizeof(child));
+		child.argv = unpacker;
+		child.no_stdout = 1;
+		child.err = err_fd;
+		child.git_cmd = 1;
+		code = run_command(&child);
 		if (!code)
 			return NULL;
 		return "unpack-objects abnormal exit";
@@ -854,6 +860,7 @@
 		memset(&ip, 0, sizeof(ip));
 		ip.argv = keeper;
 		ip.out = -1;
+		ip.err = err_fd;
 		ip.git_cmd = 1;
 		status = start_command(&ip);
 		if (status) {
@@ -870,6 +877,26 @@
 	}
 }
 
+static const char *unpack_with_sideband(void)
+{
+	struct async muxer;
+	const char *ret;
+
+	if (!use_sideband)
+		return unpack(0);
+
+	memset(&muxer, 0, sizeof(muxer));
+	muxer.proc = copy_to_sideband;
+	muxer.in = -1;
+	if (start_async(&muxer))
+		return NULL;
+
+	ret = unpack(muxer.in);
+
+	finish_async(&muxer);
+	return ret;
+}
+
 static void report(struct command *commands, const char *unpack_status)
 {
 	struct command *cmd;
@@ -967,7 +994,7 @@
 		const char *unpack_status = NULL;
 
 		if (!delete_only(commands))
-			unpack_status = unpack();
+			unpack_status = unpack_with_sideband();
 		execute_commands(commands, unpack_status);
 		if (pack_lockfile)
 			unlink_or_warn(pack_lockfile);
diff --git a/t/t5504-fetch-receive-strict.sh b/t/t5504-fetch-receive-strict.sh
index 35ec294..69ee13c 100755
--- a/t/t5504-fetch-receive-strict.sh
+++ b/t/t5504-fetch-receive-strict.sh
@@ -89,7 +89,7 @@
 
 cat >exp <<EOF
 To dst
-!	refs/heads/master:refs/heads/test	[remote rejected] (n/a (unpacker error))
+!	refs/heads/master:refs/heads/test	[remote rejected] (unpacker error)
 EOF
 
 test_expect_success 'push with receive.fsckobjects' '