diff --git a/src/fot.rs b/src/fot.rs
index caf4488..e5829f2 100644
--- a/src/fot.rs
+++ b/src/fot.rs
@@ -1,5 +1,6 @@
 mod decoder;
 mod entity;
+mod entitylist;
 mod esh;
 mod fstring;
 mod raw;
diff --git a/src/fot/decoder.rs b/src/fot/decoder.rs
index 5ec8a33..7800edf 100644
--- a/src/fot/decoder.rs
+++ b/src/fot/decoder.rs
@@ -8,9 +8,8 @@ pub trait Decoder: Sized {
     fn get_enc_size(&self) -> usize;
 }
 
-pub trait DecoderOpt: Sized {
-    type Opt<'o>;
-    fn decode(raw: &Raw, offset: usize, size: usize, opt: Option<Self::Opt<'_>>) -> Result<Self>;
+pub trait DecoderOpt<Opt>: Sized {
+    fn decode(raw: &Raw, offset: usize, size: usize, opt: Opt) -> Result<Self>;
     fn encode(&self) -> Result<Raw>;
     fn get_enc_size(&self) -> usize;
 }
diff --git a/src/fot/entity.rs b/src/fot/entity.rs
index c386a5e..3c0562f 100644
--- a/src/fot/entity.rs
+++ b/src/fot/entity.rs
@@ -1,57 +1,24 @@
-use super::raw::Raw;
-use super::tag::Tag;
-use super::esh::ESH;
 use super::decoder::DecoderOpt;
+use super::entitylist::{EntityEncoding, EntityList};
+use super::esh::ESH;
 use super::fstring::FString;
+use super::raw::Raw;
 use super::stream::{ReadStream, WriteStream};
+use super::tag::Tag;
 use anyhow::anyhow;
 use anyhow::Result;
 
-pub enum EntityEncoding {
-    File,
-    World
-}
-
-pub struct EntityList {}
-
-impl EntityList {
-    fn get_entity_encoding(&self) -> EntityEncoding {
-        todo!();
-    }
-    
-    fn get_entity_tag(&self) -> &Tag {
-        todo!();
-    }
-
-    fn add_new_type(&mut self, name: FString) -> usize {
-        todo!();
-    }
-
-    fn add_or_get_type(&mut self, name: FString) -> usize {
-        todo!();
-    }
-
-    fn get_type_name(&self, type_idx: usize) -> &FString {
-        todo!();
-    }
-}
-
 pub struct Entity {
     pub flags: u32,
     pub type_idx: usize,
     pub esh: ESH,
-    enc_size: usize
+    enc_size: usize,
 }
 
-impl DecoderOpt for Entity {
-    type Opt<'o> = &'o EntityList;
-    fn decode<'o>(raw: &Raw, offset: usize, _: usize, opt: Option<Self::Opt<'o>>) -> Result<Self> {
-        let rd = ReadStream::new(raw, offset);
-        let opt = match opt {
-            Some(opt) => opt,
-            None => return Err(anyhow!("no EntityOpt was provided!"))
-        };
-        
+impl DecoderOpt<&EntityList> for Entity {
+    fn decode(raw: &Raw, offset: usize, _: usize, opt: &EntityList) -> Result<Self> {
+        let mut rd = ReadStream::new(raw, offset);
+
         todo!();
     }
 
diff --git a/src/fot/entitylist.rs b/src/fot/entitylist.rs
new file mode 100644
index 0000000..85bed0a
--- /dev/null
+++ b/src/fot/entitylist.rs
@@ -0,0 +1,38 @@
+use super::decoder::DecoderOpt;
+use super::entity::Entity;
+use super::esh::ESH;
+use super::fstring::FString;
+use super::raw::Raw;
+use super::stream::{ReadStream, WriteStream};
+use super::tag::Tag;
+use anyhow::anyhow;
+use anyhow::Result;
+
+pub enum EntityEncoding {
+    File,
+    World,
+}
+
+pub struct EntityList {}
+
+impl EntityList {
+    fn get_entity_encoding(&self) -> EntityEncoding {
+        todo!();
+    }
+
+    fn get_entity_tag(&self) -> &Tag {
+        todo!();
+    }
+
+    fn add_new_type(&mut self, name: FString) -> usize {
+        todo!();
+    }
+
+    fn add_or_get_type(&mut self, name: FString) -> usize {
+        todo!();
+    }
+
+    fn get_type_name(&self, type_idx: usize) -> &FString {
+        todo!();
+    }
+}
diff --git a/src/fot/stream.rs b/src/fot/stream.rs
index b7e166d..50dac4b 100644
--- a/src/fot/stream.rs
+++ b/src/fot/stream.rs
@@ -46,8 +46,8 @@ impl<'a> ReadStream<'a> {
 
     // read_opt - decode with optional paramters. required for complex structure
     // with different origins (save / entfile) like entities
-    pub fn read_opt<'o, T: DecoderOpt>(&mut self, size: usize, opt: T::Opt<'o>) -> Result<T> {
-        let val = T::decode(&self.raw, self.offset(), size, Some(opt))?;
+    pub fn read_opt<T: DecoderOpt<Opt>, Opt>(&mut self, size: usize, opt: Opt) -> Result<T> {
+        let val = T::decode(&self.raw, self.offset(), size, opt)?;
         self.skip(val.get_enc_size());
         Ok(val)
     }