diff --git a/lib/dialyxir/warnings/invalid_contract.ex b/lib/dialyxir/warnings/invalid_contract.ex
index 2f86a51..95cb0f6 100644
--- a/lib/dialyxir/warnings/invalid_contract.ex
+++ b/lib/dialyxir/warnings/invalid_contract.ex
@@ -31,7 +31,11 @@ defmodule Dialyxir.Warnings.InvalidContract do
 
   @impl Dialyxir.Warning
   @spec format_long([String.t()]) :: String.t()
-  def format_long([module, function, arity, _args, signature | _]) do
+  def format_long([module, function, arity, signature]) do
+    format_long([module, function, arity, nil, signature])
+  end
+
+  def format_long([module, function, arity, _args, signature]) do
     pretty_module = Erlex.pretty_print(module)
     pretty_signature = Erlex.pretty_print_contract(signature)