diff --git a/test/unit/fiob.c b/test/unit/fiob.c
index 6bb8d2731c7dfd12d7a4e828fe7b46b76329d1e8..aa66d1187cb66f11d0b275259ad3834f2d75e96e 100644
--- a/test/unit/fiob.c
+++ b/test/unit/fiob.c
@@ -79,6 +79,10 @@ main(void)
 
 	char *td = mkdtemp(strdup("/tmp/fiob.XXXXXX"));
 	isnt(td, NULL, "tempdir is created");
+	if (td == 0) {
+		diag("Can't create temporary dir: %s", strerror(errno));
+		return -1;
+	}
 
 	static char buf[4096];