diff --git a/crates/dekoder/src/inventory.rs b/crates/dekoder/src/inventory.rs
index ab1ce8cde..c46115f20 100644
--- a/crates/dekoder/src/inventory.rs
+++ b/crates/dekoder/src/inventory.rs
@@ -14,7 +14,9 @@ const HEADER_EXT: &'static str = "*.yaml";
 /// Header type in an inventory.
 pub(crate) trait HeaderT {
     /// Load from yaml.
-    fn load_from_yaml(yml: &Yaml) -> Result<Box<Self>>;
+    fn load_from_yaml(yml: &Yaml) -> Result<Self>
+    where
+        Self: Sized;
     /// Comparator.
     fn eq(&self, other: &Self, ulps: i64) -> bool;
 }
@@ -32,7 +34,7 @@ pub(crate) struct Inventory<K: HeaderT> {
     /// Working directory
     pub(crate) path: PathBuf,
     /// Available keys
-    pub(crate) keys: HashMap<OsString, Box<K>>,
+    pub(crate) keys: HashMap<OsString, K>,
 }
 
 impl<K: HeaderT> Inventory<K> {
@@ -62,7 +64,7 @@ impl<K: HeaderT> Inventory<K> {
     }
 
     /// List available keys.
-    pub fn keys(&self) -> Vec<&Box<K>> {
+    pub fn keys(&self) -> Vec<&K> {
         let mut ks = Vec::new();
         for k in self.keys.values() {
             ks.push(k);
diff --git a/crates/dekoder/src/lib.rs b/crates/dekoder/src/lib.rs
index 79b3ce32a..6d986de63 100644
--- a/crates/dekoder/src/lib.rs
+++ b/crates/dekoder/src/lib.rs
@@ -13,6 +13,8 @@ use yaml_rust2::Yaml;
 
 mod inventory;
 
+use crate::inventory::HeaderT;
+
 /// The EKO errors.
 #[derive(Error, Debug)]
 pub enum EKOError {
@@ -43,7 +45,7 @@ pub struct EvolutionPoint {
 
 impl inventory::HeaderT for EvolutionPoint {
     /// Load from yaml.
-    fn load_from_yaml(yml: &Yaml) -> Result<Box<Self>> {
+    fn load_from_yaml(yml: &Yaml) -> Result<Self> {
         // work around float representation
         let scale = yml["scale"].as_f64();
         let scale = if scale.is_some() {
@@ -58,15 +60,22 @@ impl inventory::HeaderT for EvolutionPoint {
         let nf = yml["nf"]
             .as_i64()
             .ok_or(EKOError::KeyError("because failed to read nf".to_owned()))?;
-        Ok(Box::new(Self { scale, nf }))
+        Ok(Self { scale, nf })
     }
 
-    /// Comparator.
+    /// (Protected) comparator.
     fn eq(&self, other: &Self, ulps: i64) -> bool {
         self.nf == other.nf && approx_eq!(f64, self.scale, other.scale, ulps = ulps)
     }
 }
 
+impl EvolutionPoint {
+    /// Comparator.
+    pub fn equals(&self, other: &Self, ulps: i64) -> bool {
+        self.eq(other, ulps)
+    }
+}
+
 /// 4D evolution operator.
 pub struct Operator {
     pub op: Array4<f64>,
@@ -203,7 +212,7 @@ impl EKO {
     }
 
     /// List available evolution points.
-    pub fn available_operators(&self) -> Vec<&Box<EvolutionPoint>> {
+    pub fn available_operators(&self) -> Vec<&EvolutionPoint> {
         self.operators.keys()
     }
 
diff --git a/crates/dekoder/tests/test_load.rs b/crates/dekoder/tests/test_load.rs
index d6461cc01..bb999ddb9 100644
--- a/crates/dekoder/tests/test_load.rs
+++ b/crates/dekoder/tests/test_load.rs
@@ -59,6 +59,8 @@ fn has_operator() {
         scale: 10000.,
         nf: 4,
     };
+    // it is the one
+    assert!(ep.equals(eko.available_operators()[0], 64));
     assert!(eko.has_operator(&ep, 64));
     eko.close(false).unwrap();
 }