--- a/spec/util_format_spec.lua	Sat Mar 17 19:43:20 2018 +0100
+++ b/spec/util_format_spec.lua	Sat Mar 17 19:47:48 2018 +0100
@@ -5,6 +5,7 @@
 		it("should work", function()
 			assert.equal("hello", format("%s", "hello"));
 			assert.equal("<nil>", format("%s"));
+			assert.equal(" [<nil>]", format("", nil));
 			assert.equal("true", format("%s", true));
 			assert.equal("[true]", format("%d", true));
 			assert.equal("% [true]", format("%%", true));