--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/empty.rs	Fri Dec 02 21:03:43 2022 +0100
@@ -0,0 +1,18 @@
+//! Reproduces (verifies) issue #17: Panics when used on fn without args.
+
+use memoize::memoize;
+
+#[memoize]
+fn hello() -> bool {
+    println!("hello!");
+    true
+}
+
+fn main() {
+    // `hello` is only called once here.
+    assert!(hello());
+    assert!(hello());
+    memoized_flush_hello();
+    // and again here.
+    assert!(hello());
+}

--- a/inner/src/lib.rs	Fri Oct 21 19:05:50 2022 +0200
+++ b/inner/src/lib.rs	Fri Dec 02 21:03:43 2022 +0100
@@ -221,12 +221,11 @@
         Ok((t, n)) => {
             input_types = t;
             input_names = n;
-        }
+        },
         Err(e) => return e.to_compile_error().into(),
     }
 
     let input_tuple_type = quote::quote! { (#(#input_types),*) };
-
     match &sig.output {
         syn::ReturnType::Default => return_type = quote::quote! { () },
         syn::ReturnType::Type(_, ty) => return_type = ty.to_token_stream(),
@@ -339,6 +338,9 @@
 fn check_signature(
     sig: &syn::Signature,
 ) -> Result<(Vec<Box<syn::Type>>, Vec<syn::Ident>), syn::Error> {
+    if sig.inputs.is_empty() {
+        return Ok((vec![], vec![]));
+    }
     if let syn::FnArg::Receiver(_) = sig.inputs[0] {
         return Err(syn::Error::new(
             sig.span(),