diff --git a/test/unit/thread.c b/test/unit/thread.c
index 482856f..1bbecc2 100644
--- a/test/unit/thread.c
+++ b/test/unit/thread.c
@@ -1,8 +1,31 @@
+#include "unittest.h"
 #include "emu/thread.h"
-#include "common.h"
 
+/* Ensure we can load the old trace format */
+static void
+test_old_trace(void)
+{
+	struct thread th;
+
+	OK(thread_init_begin(&th, "loom.0/proc.0/thread.1.obs"));
+	if (th.tid != 1)
+		die("wrong tid");
+
+	OK(thread_init_begin(&th, "loom.0/proc.0/thread.2"));
+	if (th.tid != 2)
+		die("wrong tid");
+
+	ERR(thread_init_begin(&th, "loom.0/proc.0/thread.kk"));
+	ERR(thread_init_begin(&th, "loom.0/proc.0/thread."));
+	ERR(thread_init_begin(&th, "loom.0/proc.0/thread"));
+	ERR(thread_init_begin(&th, "thread.prv"));
+
+	err("ok");
+}
 
 int main(void)
 {
+	test_old_trace();
+
 	return 0;
 }