diff --git a/tests/unit/test-io-channel-command.c b/tests/unit/test-io-channel-command.c
index c6e66a8c33..4f022617df 100644
--- a/tests/unit/test-io-channel-command.c
+++ b/tests/unit/test-io-channel-command.c
@@ -35,7 +35,7 @@ static char *socat = NULL;
 static void test_io_channel_command_fifo(bool async)
 {
     g_autofree gchar *tmpdir = g_dir_make_tmp("qemu-test-io-channel.XXXXXX", NULL);
-    g_autofree gchar *fifo = g_strdup_printf("%s/%s", tmpdir, TEST_FIFO);
+    g_autofree gchar *fifo = g_build_filename(tmpdir, TEST_FIFO, NULL);
     g_autofree gchar *srcargs = g_strdup_printf("%s - PIPE:%s,wronly", socat, fifo);
     g_autofree gchar *dstargs = g_strdup_printf("%s PIPE:%s,rdonly -", socat, fifo);
     g_auto(GStrv) srcargv = g_strsplit(srcargs, " ", -1);