diff --git a/core/extensions.rs b/core/extensions.rs
index 2454185b7..00bb624fd 100644
--- a/core/extensions.rs
+++ b/core/extensions.rs
@@ -369,11 +369,13 @@ macro_rules! or {
 ///  * lazy_loaded_esm: a comma-separated list of ESM module filenames (see [`include_js_files`]), that will be included in
 ///     the produced binary, but not automatically evaluated. Eg: `lazy_loaded_esm = [ dir "dir", "my_file.js" ]`
 ///  * js: a comma-separated list of JS filenames (see [`include_js_files`]), eg: `js = [ dir "dir", "my_file.js" ]`
-///  * config: a structure-like definition for configuration parameters which will be required when initializing this extension, eg: `config = { my_param: Option<usize> }`
+///  * options: a structure-like definition for configuration parameters which will be required when initializing this extension, eg: `options = { my_param: Option<usize> }`
 ///  * middleware: an [`OpDecl`] middleware function with the signature `fn (OpDecl) -> OpDecl`
-///  * state: a state initialization function, with the signature `fn (&mut OpState, ...) -> ()`, where `...` are parameters matching the fields of the config struct
+///  * state: a state initialization function, with the signature `fn (&mut OpState, ...) -> ()`, where `...` are parameters matching the fields of the options struct
 ///  * global_template_middleware: a global template middleware function (see [`Extension::global_template_middleware`])
 ///  * global_object_middleware: a global object middleware function (see [`Extension::global_object_middleware`])
+///  * external_references: a comma-separated list of [`v8::ExternalReference`], eg: `external_references = [ ref1, ref2 ]`
+///  * customizer: a customizer function with the signature `fn (&mut Extension) -> ()`, eg. `customizer = |ext: &mut deno_core::Extension| { ext.enabled = false; }`
 ///  * docs: comma separated list of toplevel #[doc=...] tags to be applied to the extension's resulting struct
 #[macro_export]
 macro_rules! extension {
@@ -447,7 +449,7 @@ macro_rules! extension {
             $( #[ $m ] )*
             $( $op )::+ $( :: < $($op_param),* > )? ()
           }),+)?]),
-          external_references: ::std::borrow::Cow::Borrowed(&[ $( $external_reference ),* ]),
+          external_references: ::std::borrow::Cow::Borrowed(&[ $( $( $external_reference ),* )? ]),
           global_template_middleware: ::std::option::Option::None,
           global_object_middleware: ::std::option::Option::None,
           // Computed at runtime:
@@ -473,7 +475,7 @@ macro_rules! extension {
       fn with_state_and_middleware$( <  $( $param : $type + 'static ),+ > )?(ext: &mut $crate::Extension, $( $( $options_id : $options_type ),* )? )
       $( where $( $bound : $bound_type ),+ )?
       {
-        $crate::extension!(! __config__ ext $( parameters = [ $( $param : $type ),* ] )? $( config = { $( $options_id : $options_type ),* } )? $( state_fn = $state_fn )? );
+        $crate::__internal__extension_config_state_fn!(ext $( parameters = [ $( $param : $type ),* ] )? $( config = { $( $options_id : $options_type ),* } )? $( state_fn = $state_fn )? );
 
         $(
           ext.global_template_middleware = ::std::option::Option::Some($global_template_middleware_fn);
@@ -536,8 +538,37 @@ macro_rules! extension {
     }
   };
 
-  // This branch of the macro generates a config object that calls the state function with itself.
-  (! __config__ $ext:ident $( parameters = [ $( $param:ident : $type:ident ),+ ] )? config = { $( $options_id:ident : $options_type:ty ),* } $( state_fn = $state_fn:expr )? ) => {
+  (! __ops__ $ext:ident __eot__) => {
+  };
+
+  (! __ops__ $ext:ident $ops_symbol:ident __eot__) => {
+    $ext.ops.to_mut().extend($ops_symbol())
+  };
+
+  (! __ops__ $ext:ident $ops_symbol:ident < $ops_param:ident > __eot__) => {
+    $ext.ops.to_mut().extend($ops_symbol::<$ops_param>())
+  };
+}
+
+// This private macro generates a config object that calls the state_fn with
+// itself, depending on the presence of the config and state_fn.
+#[macro_export]
+macro_rules! __internal__extension_config_state_fn {
+  // Neither config nor state_fn are provided
+  ($ext:ident $( parameters = [ $( $param:ident : $type:ident ),+ ] )? ) => {
+  };
+
+  // Config values are provided, but state_fn is not
+  ($ext:ident $( parameters = [ $( $param:ident : $type:ident ),+ ] )? config = { $( $options_id:ident : $options_type:ty ),* }) => {
+  };
+
+  // Config values are not provided, but state_fn is
+  ($ext:ident $( parameters = [ $( $param:ident : $type:ident ),+ ] )? state_fn = $state_fn:expr ) => {
+    $ext.op_state_fn = ::std::option::Option::Some(::std::boxed::Box::new($state_fn));
+  };
+
+  // Both config values and state_fn are provided
+  ($ext:ident $( parameters = [ $( $param:ident : $type:ident ),+ ] )? config = { $( $options_id:ident : $options_type:ty ),* } state_fn = $state_fn:expr ) => {
     {
       #[doc(hidden)]
       struct Config $( <  $( $param : $type + 'static ),+ > )? {
@@ -549,27 +580,12 @@ macro_rules! extension {
         $( __phantom_data: ::std::marker::PhantomData::<($( $param ),+)>::default() )?
       };
 
-      let state_fn: fn(&mut $crate::OpState, Config $( <  $( $param ),+ > )? ) = $(  $state_fn  )?;
+      let state_fn: fn(&mut $crate::OpState, Config $( <  $( $param ),+ > )? ) = $state_fn;
       $ext.op_state_fn = ::std::option::Option::Some(::std::boxed::Box::new(move |state: &mut $crate::OpState| {
         state_fn(state, config);
       }));
     }
   };
-
-  (! __config__ $ext:ident $( parameters = [ $( $param:ident : $type:ident ),+ ] )? $( state_fn = $state_fn:expr )? ) => {
-    $( $ext.op_state_fn = ::std::option::Option::Some(::std::boxed::Box::new($state_fn)); )?
-  };
-
-  (! __ops__ $ext:ident __eot__) => {
-  };
-
-  (! __ops__ $ext:ident $ops_symbol:ident __eot__) => {
-    $ext.ops.to_mut().extend($ops_symbol())
-  };
-
-  (! __ops__ $ext:ident $ops_symbol:ident < $ops_param:ident > __eot__) => {
-    $ext.ops.to_mut().extend($ops_symbol::<$ops_param>())
-  };
 }
 
 pub struct Extension {