diff --git a/test.lua b/test.lua
index 731b220..8ce6681 100644
--- a/test.lua
+++ b/test.lua
@@ -52,6 +52,10 @@ local tests = {
 	},
 
 	extra = {
+		printfmt = function ()
+			printfmt("Testing %s (%d)", "printfmt", os.time())
+			return 'printfmt("Testing %%s (%%d)", ...)'
+		end
 	},
 
 	fs = {
@@ -216,6 +220,9 @@ do
 	test(environ.set)
 	test(environ.pairs)
 
+	-- extra
+	test(extra.printfmt)
+
 	-- fs
 	test(fs.copy)
 	test(fs.directory)