diff --git a/builtin/common/serialize.lua b/builtin/common/serialize.lua
index 1054f8eac..b7643b2f4 100644
--- a/builtin/common/serialize.lua
+++ b/builtin/common/serialize.lua
@@ -140,7 +140,7 @@ function core.serialize(x)
 			end
 			return "{"..table.concat(vals, ", ").."}"
 		else
-			error("Can't serialize data of type "..t)
+			error("Can't serialize data of type "..tp)
 		end
 	end