diff --git a/assert.lua b/assert.lua
index 8cfccb0..d318b1c 100644
--- a/assert.lua
+++ b/assert.lua
@@ -90,9 +90,14 @@ function assert:one_of(a, t, msg, stack_level)
 		end
 	end
 
+	local values = {}
+	for index = 1, #t do
+		values[index] = tostring(t[index])
+	end
+
 	error(("assertion failed: %s not one of %s %s"):format(
 		tostring(a),
-		table.concat(t, ", "),
+		table.concat(values, ", "),
 		_extra(msg)
 	), 2 + (stack_level or 0))
 end