diff --git a/Cargo.toml b/Cargo.toml
index 1186389d5..87e813095 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,4 +1,5 @@
 [workspace]
+resolver = "2"
 
 members = [
     "rascaline",
diff --git a/docs/rascaline-json-schema/Cargo.toml b/docs/rascaline-json-schema/Cargo.toml
index 3afea40b0..c6fea5aa1 100644
--- a/docs/rascaline-json-schema/Cargo.toml
+++ b/docs/rascaline-json-schema/Cargo.toml
@@ -2,7 +2,7 @@
 name = "rascaline-json-schema"
 version = "0.1.0"
 authors = ["Luthaf <luthaf@luthaf.fr>"]
-edition = "2018"
+edition = "2021"
 publish = false
 rust-version = "1.64"
 
diff --git a/rascaline/src/calculator.rs b/rascaline/src/calculator.rs
index e5fd32be0..9e32ad288 100644
--- a/rascaline/src/calculator.rs
+++ b/rascaline/src/calculator.rs
@@ -57,7 +57,7 @@ impl<'a> LabelsSelection<'a> {
     {
         assert_ne!(keys.count(), 0);
 
-        match self {
+        match *self {
             LabelsSelection::All => {
                 return get_default_labels(keys);
             },
@@ -69,7 +69,7 @@ impl<'a> LabelsSelection<'a> {
                 if selection.names() == default_names {
                     for labels in default_labels {
                         let mut builder = LabelsBuilder::new(default_names.clone());
-                        for entry in selection.iter() {
+                        for entry in selection {
                             if labels.contains(entry) {
                                 builder.add(entry);
                             }
@@ -93,8 +93,8 @@ impl<'a> LabelsSelection<'a> {
 
                     for labels in default_labels {
                         let mut builder = LabelsBuilder::new(default_names.clone());
-                        for entry in labels.iter() {
-                            for selected in selection.iter() {
+                        for entry in &labels {
+                            for selected in selection {
                                 let mut matches = true;
                                 for (i, &v) in variables_to_match.iter().enumerate() {
                                     if selected[i] != entry[v] {
@@ -124,7 +124,7 @@ impl<'a> LabelsSelection<'a> {
                         tensor.keys().names().join(", ")
                     )));
                 }
-                for key in keys.iter() {
+                for key in keys {
                     if !tensor.keys().contains(key) {
                         let key_print = keys.names().iter()
                             .zip(key)
diff --git a/rascaline/src/calculators/atomic_composition.rs b/rascaline/src/calculators/atomic_composition.rs
index 2c8a3107a..ed2c0696b 100644
--- a/rascaline/src/calculators/atomic_composition.rs
+++ b/rascaline/src/calculators/atomic_composition.rs
@@ -115,7 +115,7 @@ impl CalculatorBase for AtomicComposition {
     ) -> Result<(), Error> {
         assert_eq!(descriptor.keys().names(), ["species_center"]);
 
-        for (key, mut block) in descriptor.iter_mut() {
+        for (key, mut block) in descriptor {
             let species_center = key[0].i32();
 
             let block = block.data_mut();
diff --git a/rascaline/src/calculators/dummy_calculator.rs b/rascaline/src/calculators/dummy_calculator.rs
index f5340d052..389985d8b 100644
--- a/rascaline/src/calculators/dummy_calculator.rs
+++ b/rascaline/src/calculators/dummy_calculator.rs
@@ -117,7 +117,7 @@ impl CalculatorBase for DummyCalculator {
             warn!("{}", self.name);
         }
 
-        for (key, mut block) in descriptor.iter_mut() {
+        for (key, mut block) in descriptor {
             let species_center = key[0].i32();
 
             let block_data = block.data_mut();
diff --git a/rascaline/src/calculators/lode/spherical_expansion.rs b/rascaline/src/calculators/lode/spherical_expansion.rs
index 62a2a192a..41474a990 100644
--- a/rascaline/src/calculators/lode/spherical_expansion.rs
+++ b/rascaline/src/calculators/lode/spherical_expansion.rs
@@ -637,7 +637,7 @@ impl CalculatorBase for LodeSphericalExpansion {
 
                     let k_vector_to_m_n = &k_vector_to_m_n[spherical_harmonics_l];
 
-                    for (&species_neighbor, sf_per_center) in sf_per_center.iter() {
+                    for (&species_neighbor, sf_per_center) in sf_per_center {
                         for center_i in 0..system.size()? {
                             let block_i = descriptor.keys().position(&[
                                 spherical_harmonics_l.into(),
diff --git a/rascaline/src/calculators/soap/power_spectrum.rs b/rascaline/src/calculators/soap/power_spectrum.rs
index c5eb2b916..3cb076f0d 100644
--- a/rascaline/src/calculators/soap/power_spectrum.rs
+++ b/rascaline/src/calculators/soap/power_spectrum.rs
@@ -227,7 +227,7 @@ impl SoapPowerSpectrum {
         spherical_expansion: &TensorMap
     ) -> HashMap<Vec<LabelValue>, SamplesMapping> {
         let mut mapping = HashMap::new();
-        for (key, block) in descriptor.iter() {
+        for (key, block) in descriptor {
             let species_center = key[0];
             let species_neighbor_1 = key[1];
             let species_neighbor_2 = key[2];
@@ -554,7 +554,7 @@ impl CalculatorBase for SoapPowerSpectrum {
             (key, spx_block)
         }).collect();
 
-        for (key, mut block) in descriptor.iter_mut() {
+        for (key, mut block) in descriptor {
             let species_neighbor_1 = key[1];
             let species_neighbor_2 = key[2];
 
diff --git a/rascaline/src/calculators/soap/spherical_expansion.rs b/rascaline/src/calculators/soap/spherical_expansion.rs
index 8ba400733..84f1b6c43 100644
--- a/rascaline/src/calculators/soap/spherical_expansion.rs
+++ b/rascaline/src/calculators/soap/spherical_expansion.rs
@@ -50,7 +50,7 @@ impl SphericalExpansion {
 
         let self_contribution = self.by_pair.self_contribution();
 
-        for (key, mut block) in descriptor.iter_mut() {
+        for (key, mut block) in descriptor {
             let spherical_harmonics_l = key[0];
             let species_center = key[1];
             let species_neighbor = key[2];
diff --git a/rascaline/src/calculators/soap/spherical_expansion_pair.rs b/rascaline/src/calculators/soap/spherical_expansion_pair.rs
index 959abaf7f..105e6e5f8 100644
--- a/rascaline/src/calculators/soap/spherical_expansion_pair.rs
+++ b/rascaline/src/calculators/soap/spherical_expansion_pair.rs
@@ -266,7 +266,7 @@ impl SphericalExpansionByPair {
         debug_assert_eq!(descriptor.keys().names(), ["spherical_harmonics_l", "species_atom_1", "species_atom_2"]);
         let self_contribution = self.self_contribution();
 
-        for (key, mut block) in descriptor.iter_mut() {
+        for (key, mut block) in descriptor {
             let spherical_harmonics_l = key[0];
             let species_atom_1 = key[1];
             let species_atom_2 = key[2];
@@ -373,7 +373,7 @@ impl SphericalExpansionByPair {
             let radial_integral = radial_integral.values.slice(s![spherical_harmonics_l, ..]);
 
             // compute the full spherical expansion coefficients & gradients
-            for sph_value in spherical_harmonics.iter() {
+            for sph_value in spherical_harmonics {
                 for (n, ri_value) in radial_integral.iter().enumerate() {
                     contribution.values[[lm_index, n]] = f_scaling * sph_value * ri_value;
                 }
diff --git a/rascaline/src/calculators/sorted_distances.rs b/rascaline/src/calculators/sorted_distances.rs
index 4cbdeeef8..bfdbe9ccb 100644
--- a/rascaline/src/calculators/sorted_distances.rs
+++ b/rascaline/src/calculators/sorted_distances.rs
@@ -122,7 +122,7 @@ impl CalculatorBase for SortedDistances {
             assert_eq!(descriptor.keys().names(), ["species_center"]);
         }
 
-        for (key, mut block) in descriptor.iter_mut() {
+        for (key, mut block) in descriptor {
             let species_neighbor = if self.separate_neighbor_species {
                 Some(key[1].i32())
             } else {