diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index ac6cfb3..76e5fdd 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -36,7 +36,7 @@ jobs:
         target:
           - aarch64-unknown-linux-gnu
           - i686-unknown-linux-gnu
-          - mips64-unknown-linux-gnuabi64
+          - powerpc-unknown-linux-gnu
     steps:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
@@ -90,7 +90,7 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: 1.54.0
+          toolchain: 1.66.0
           override: true
       - run: rustup component add clippy
       - uses: actions-rs/cargo@v1
diff --git a/.gitignore b/.gitignore
index c452573..1f076f7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 .*
 *.bk
 target
+/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
index b5e028b..38dea09 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,8 +1,8 @@
 [package]
 name = "finalfusion"
-version = "0.17.1"
-edition = "2018"
-authors = ["Daniël de Kok <me@danieldk.eu>", "Sebastian Pütz <seb.puetz@gmail.com>"]
+version = "0.18.0"
+edition = "2021"
+rust-version = "1.66"
 description = "Reader and writer for common word embedding formats"
 documentation = "https://docs.rs/finalfusion/"
 keywords = ["embeddings", "word2vec", "glove", "finalfusion", "fasttext"]
@@ -10,28 +10,25 @@ homepage = "https://github.com/finalfusion/finalfusion-rust"
 repository = "https://github.com/finalfusion/finalfusion-rust"
 license = "MIT OR Apache-2.0"
 readme = "README.md"
-exclude = [
-  ".gitignore",
-  ".travis.yml"
-]
+exclude = [".gitignore"]
 
 [dependencies]
 byteorder = "1"
 fnv = "1"
-itertools = "0.10"
+itertools = "0.11"
 murmur3 = "0.5"
-ndarray = "0.15"
-ordered-float = "2"
+ndarray = { version = "0.15", features = ["approx-0_5"] }
+ordered-float = "4"
 rand = "0.8"
 rand_chacha = "0.3"
 reductive = "0.9"
 serde = { version = "1", features = ["derive"] }
 smallvec = "1.7"
 thiserror = "1"
-toml = "0.5"
+toml = "0.8"
 
 [dependencies.memmap2]
-version = "0.5"
+version = "0.9"
 optional = true
 
 [features]
@@ -39,8 +36,8 @@ default = ["memmap"]
 memmap = ["memmap2"]
 
 [dev-dependencies]
-approx = "0.4"
-criterion = "0.3"
+approx = "0.5"
+criterion = "0.5"
 lazy_static = "1"
 maplit = "1"
 tempfile = "3"
diff --git a/benches/array.rs b/benches/array.rs
index 32c79ea..b849ae7 100644
--- a/benches/array.rs
+++ b/benches/array.rs
@@ -25,18 +25,18 @@ fn allround_iter() -> impl Iterator<Item = String> + Clone {
     corpus.into_iter()
 }
 
-fn known_iter<'a>(
-    embeds: &'a Embeddings<VocabWrap, StorageWrap>,
-) -> impl 'a + Iterator<Item = String> + Clone {
+fn known_iter(
+    embeds: &Embeddings<VocabWrap, StorageWrap>,
+) -> impl '_ + Iterator<Item = String> + Clone {
     allround_iter().filter_map(move |w| match embeds.vocab().idx(&w) {
         Some(WordIndex::Word(_)) => Some(w),
         _ => None,
     })
 }
 
-fn unknown_iter<'a>(
-    embeds: &'a Embeddings<VocabWrap, StorageWrap>,
-) -> impl 'a + Iterator<Item = String> + Clone {
+fn unknown_iter(
+    embeds: &Embeddings<VocabWrap, StorageWrap>,
+) -> impl '_ + Iterator<Item = String> + Clone {
     allround_iter().filter_map(move |w| match embeds.vocab().idx(&w) {
         Some(WordIndex::Subword(_)) => Some(w),
         _ => None,
diff --git a/benches/quantized.rs b/benches/quantized.rs
index 655725b..5029818 100644
--- a/benches/quantized.rs
+++ b/benches/quantized.rs
@@ -25,18 +25,18 @@ fn allround_iter() -> impl Iterator<Item = String> + Clone {
     corpus.into_iter()
 }
 
-fn known_iter<'a>(
-    embeds: &'a Embeddings<VocabWrap, StorageWrap>,
-) -> impl 'a + Iterator<Item = String> + Clone {
+fn known_iter(
+    embeds: &Embeddings<VocabWrap, StorageWrap>,
+) -> impl '_ + Iterator<Item = String> + Clone {
     allround_iter().filter_map(move |w| match embeds.vocab().idx(&w) {
         Some(WordIndex::Word(_)) => Some(w),
         _ => None,
     })
 }
 
-fn unknown_iter<'a>(
-    embeds: &'a Embeddings<VocabWrap, StorageWrap>,
-) -> impl 'a + Iterator<Item = String> + Clone {
+fn unknown_iter(
+    embeds: &Embeddings<VocabWrap, StorageWrap>,
+) -> impl '_ + Iterator<Item = String> + Clone {
     allround_iter().filter_map(move |w| match embeds.vocab().idx(&w) {
         Some(WordIndex::Subword(_)) => Some(w),
         _ => None,
diff --git a/benches/subword.rs b/benches/subword.rs
index 5b47c8b..eafb0b0 100644
--- a/benches/subword.rs
+++ b/benches/subword.rs
@@ -13,7 +13,6 @@ fn subwords(string: &str, min_n: usize, max_n: usize, indexer: &impl Indexer) ->
     // evaluates them.
     string
         .subword_indices(min_n, max_n, indexer)
-        .into_iter()
         .fold(0, |sum, v| sum.wrapping_add(v))
 }
 
diff --git a/src/chunks/io.rs b/src/chunks/io.rs
index d59de49..c25a25f 100644
--- a/src/chunks/io.rs
+++ b/src/chunks/io.rs
@@ -1,4 +1,3 @@
-use std::convert::TryFrom;
 use std::fmt::{self, Display};
 use std::fs::File;
 use std::io::{BufReader, Read, Seek, Write};
diff --git a/src/chunks/metadata.rs b/src/chunks/metadata.rs
index 0b0fffa..eef1048 100644
--- a/src/chunks/metadata.rs
+++ b/src/chunks/metadata.rs
@@ -5,7 +5,7 @@ use std::mem;
 use std::ops::{Deref, DerefMut};
 
 use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
-use toml::Value;
+use toml::Table;
 
 use crate::chunks::io::{ChunkIdentifier, Header, ReadChunk, WriteChunk};
 use crate::error::{Error, Result};
@@ -16,18 +16,18 @@ use crate::io::ReadMetadata;
 /// finalfusion metadata in TOML format.
 #[derive(Clone, Debug, PartialEq)]
 pub struct Metadata {
-    inner: Value,
+    inner: Table,
 }
 
 impl Metadata {
     /// Construct new `Metadata`.
-    pub fn new(data: Value) -> Self {
-        Metadata { inner: data }
+    pub fn new(inner: Table) -> Self {
+        Metadata { inner }
     }
 }
 
 impl Deref for Metadata {
-    type Target = Value;
+    type Target = Table;
 
     fn deref(&self) -> &Self::Target {
         &self.inner
@@ -40,9 +40,9 @@ impl DerefMut for Metadata {
     }
 }
 
-impl From<Value> for Metadata {
-    fn from(value: Value) -> Self {
-        Metadata { inner: value }
+impl From<Table> for Metadata {
+    fn from(inner: Table) -> Self {
+        Metadata { inner }
     }
 }
 
@@ -69,7 +69,7 @@ impl ReadChunk for Metadata {
 
         Ok(Metadata::new(
             buf_str
-                .parse::<Value>()
+                .parse::<Table>()
                 .map_err(|e| Error::Format(format!("Cannot deserialize TOML metadata: {}", e)))
                 .map_err(Error::from)?,
         ))
diff --git a/src/chunks/norms.rs b/src/chunks/norms.rs
index 45d962c..05cd924 100644
--- a/src/chunks/norms.rs
+++ b/src/chunks/norms.rs
@@ -1,6 +1,5 @@
 //! Norms chunk
 
-use std::convert::TryInto;
 use std::io::{Read, Seek, SeekFrom, Write};
 use std::mem;
 use std::mem::size_of;
@@ -71,7 +70,7 @@ impl ReadChunk for NdNorms {
         f32::ensure_data_type(read)?;
 
         let n_padding =
-            padding::<f32>(read.seek(SeekFrom::Current(0)).map_err(|e| {
+            padding::<f32>(read.stream_position().map_err(|e| {
                 Error::read_error("Cannot get file position for computing padding", e)
             })?);
         read.seek(SeekFrom::Current(n_padding as i64))
@@ -109,12 +108,12 @@ impl WriteChunk for NdNorms {
         write
             .write_u32::<LittleEndian>(ChunkIdentifier::NdNorms as u32)
             .map_err(|e| Error::write_error("Cannot write norms chunk identifier", e))?;
-        let n_padding = padding::<f32>(write.seek(SeekFrom::Current(0)).map_err(|e| {
+        let n_padding = padding::<f32>(write.stream_position().map_err(|e| {
             Error::write_error("Cannot get file position for computing padding", e)
         })?);
 
         let remaining_chunk_len =
-            self.chunk_len(write.seek(SeekFrom::Current(0)).map_err(|e| {
+            self.chunk_len(write.stream_position().map_err(|e| {
                 Error::read_error("Cannot get file position for computing padding", e)
             })?) - (size_of::<u32>() + size_of::<u64>()) as u64;
 
diff --git a/src/chunks/storage/array.rs b/src/chunks/storage/array.rs
index 85ce794..7d0c632 100644
--- a/src/chunks/storage/array.rs
+++ b/src/chunks/storage/array.rs
@@ -1,4 +1,3 @@
-use std::convert::TryInto;
 use std::io::{Read, Seek, SeekFrom, Write};
 use std::mem;
 use std::mem::size_of;
@@ -13,7 +12,6 @@ use crate::util::padding;
 
 #[cfg(feature = "memmap")]
 mod mmap {
-    use std::convert::TryInto;
     use std::fs::File;
     #[cfg(target_endian = "little")]
     use std::io::Write;
@@ -134,7 +132,7 @@ mod mmap {
             // The components of the embedding matrix should be of type f32.
             f32::ensure_data_type(read)?;
 
-            let n_padding = padding::<f32>(read.seek(SeekFrom::Current(0)).map_err(|e| {
+            let n_padding = padding::<f32>(read.stream_position().map_err(|e| {
                 Error::read_error("Cannot get file position for computing padding", e)
             })?);
             read.seek(SeekFrom::Current(n_padding as i64))
@@ -142,7 +140,7 @@ mod mmap {
 
             // Set up memory mapping.
             let matrix_len = shape.size() * size_of::<f32>();
-            let offset = read.seek(SeekFrom::Current(0)).map_err(|e| {
+            let offset = read.stream_position().map_err(|e| {
                 Error::read_error(
                     "Cannot get file position for memory mapping embedding matrix",
                     e,
@@ -153,7 +151,7 @@ mod mmap {
                 mmap_opts
                     .offset(offset)
                     .len(matrix_len)
-                    .map(&*read.get_ref())
+                    .map(read.get_ref())
                     .map_err(|e| Error::read_error("Cannot memory map embedding matrix", e))?
             };
 
@@ -218,13 +216,13 @@ impl NdArray {
         write
             .write_u32::<LittleEndian>(ChunkIdentifier::NdArray as u32)
             .map_err(|e| Error::write_error("Cannot write embedding matrix chunk identifier", e))?;
-        let n_padding = padding::<f32>(write.seek(SeekFrom::Current(0)).map_err(|e| {
+        let n_padding = padding::<f32>(write.stream_position().map_err(|e| {
             Error::write_error("Cannot get file position for computing padding", e)
         })?);
 
         let remaining_chunk_len = Self::chunk_len(
             data.view(),
-            write.seek(SeekFrom::Current(0)).map_err(|e| {
+            write.stream_position().map_err(|e| {
                 Error::read_error("Cannot get file position for computing padding", e)
             })?,
         ) - (size_of::<u32>() + size_of::<u64>()) as u64;
@@ -346,7 +344,7 @@ impl ReadChunk for NdArray {
         f32::ensure_data_type(read)?;
 
         let n_padding =
-            padding::<f32>(read.seek(SeekFrom::Current(0)).map_err(|e| {
+            padding::<f32>(read.stream_position().map_err(|e| {
                 Error::read_error("Cannot get file position for computing padding", e)
             })?);
         read.seek(SeekFrom::Current(n_padding as i64))
diff --git a/src/chunks/storage/quantized.rs b/src/chunks/storage/quantized.rs
index 50db780..3d26c4a 100644
--- a/src/chunks/storage/quantized.rs
+++ b/src/chunks/storage/quantized.rs
@@ -1,4 +1,3 @@
-use std::convert::TryInto;
 use std::io::{Read, Seek, SeekFrom, Write};
 use std::mem;
 use std::mem::size_of;
@@ -117,7 +116,7 @@ impl QuantizedArray {
         f32::ensure_data_type(read)?;
 
         let n_padding =
-            padding::<f32>(read.seek(SeekFrom::Current(0)).map_err(|e| {
+            padding::<f32>(read.stream_position().map_err(|e| {
                 Error::read_error("Cannot get file position for computing padding", e)
             })?);
         read.seek(SeekFrom::Current(n_padding as i64))
@@ -171,12 +170,12 @@ impl QuantizedArray {
             quantizer,
             quantized.view(),
             norms,
-            write.seek(SeekFrom::Current(0)).map_err(|e| {
+            write.stream_position().map_err(|e| {
                 Error::read_error("Cannot get file position for computing padding", e)
             })?,
         ) - (size_of::<u32>() + size_of::<u64>()) as u64;
 
-        let n_padding = padding::<f32>(write.seek(SeekFrom::Current(0)).map_err(|e| {
+        let n_padding = padding::<f32>(write.stream_position().map_err(|e| {
             Error::write_error("Cannot get file position for computing padding", e)
         })?);
 
@@ -562,7 +561,7 @@ mod mmap {
             n_embeddings: usize,
             quantized_len: usize,
         ) -> Result<Mmap> {
-            let offset = read.seek(SeekFrom::Current(0)).map_err(|e| {
+            let offset = read.stream_position().map_err(|e| {
                 Error::read_error(
                     "Cannot get file position for memory mapping embedding matrix",
                     e,
@@ -574,7 +573,7 @@ mod mmap {
                 mmap_opts
                     .offset(offset)
                     .len(matrix_len)
-                    .map(&*read.get_ref())
+                    .map(read.get_ref())
                     .map_err(|e| {
                         Error::read_error("Cannot memory map quantized embedding matrix", e)
                     })?
diff --git a/src/chunks/storage/wrappers.rs b/src/chunks/storage/wrappers.rs
index 9f81cc1..f08472b 100644
--- a/src/chunks/storage/wrappers.rs
+++ b/src/chunks/storage/wrappers.rs
@@ -1,4 +1,3 @@
-use std::convert::TryFrom;
 #[cfg(feature = "memmap")]
 use std::fs::File;
 #[cfg(feature = "memmap")]
@@ -126,7 +125,7 @@ impl ReadChunk for StorageWrap {
         R: Read + Seek,
     {
         let chunk_start_pos = read
-            .seek(SeekFrom::Current(0))
+            .stream_position()
             .map_err(|e| Error::read_error("Cannot get storage chunk start position", e))?;
 
         let chunk_id = read
@@ -156,7 +155,7 @@ impl ReadChunk for StorageWrap {
 impl MmapChunk for StorageWrap {
     fn mmap_chunk(read: &mut BufReader<File>) -> Result<Self> {
         let chunk_start_pos = read
-            .seek(SeekFrom::Current(0))
+            .stream_position()
             .map_err(|e| Error::read_error("Cannot get storage chunk start position", e))?;
 
         let chunk_id = read
@@ -306,7 +305,7 @@ impl ReadChunk for StorageViewWrap {
         R: Read + Seek,
     {
         let chunk_start_pos = read
-            .seek(SeekFrom::Current(0))
+            .stream_position()
             .map_err(|e| Error::read_error("Cannot get storage chunk start position", e))?;
 
         let chunk_id = read
@@ -361,7 +360,7 @@ impl WriteChunk for StorageViewWrap {
 impl MmapChunk for StorageViewWrap {
     fn mmap_chunk(read: &mut BufReader<File>) -> Result<Self> {
         let chunk_start_pos = read
-            .seek(SeekFrom::Current(0))
+            .stream_position()
             .map_err(|e| Error::read_error("Cannot get storage chunk start position", e))?;
 
         let chunk_id = read
diff --git a/src/chunks/vocab/simple.rs b/src/chunks/vocab/simple.rs
index 2915bb8..d9922dd 100644
--- a/src/chunks/vocab/simple.rs
+++ b/src/chunks/vocab/simple.rs
@@ -1,6 +1,5 @@
 use std::collections::HashMap;
-use std::convert::TryInto;
-use std::io::{Read, Seek, SeekFrom, Write};
+use std::io::{Read, Seek, Write};
 use std::mem::size_of;
 
 use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
@@ -103,7 +102,7 @@ impl WriteChunk for SimpleVocab {
             .map_err(|e| Error::write_error("Cannot write vocabulary chunk identifier", e))?;
 
         let remaining_chunk_len =
-            self.chunk_len(write.seek(SeekFrom::Current(0)).map_err(|e| {
+            self.chunk_len(write.stream_position().map_err(|e| {
                 Error::read_error("Cannot get file position for computing padding", e)
             })?) - (size_of::<u32>() + size_of::<u64>()) as u64;
 
diff --git a/src/chunks/vocab/subword.rs b/src/chunks/vocab/subword.rs
index 325422d..253da20 100644
--- a/src/chunks/vocab/subword.rs
+++ b/src/chunks/vocab/subword.rs
@@ -1,5 +1,4 @@
 use std::collections::HashMap;
-use std::convert::TryFrom;
 use std::io;
 use std::io::{ErrorKind, Read, Seek, Write};
 use std::mem::size_of;
@@ -400,7 +399,7 @@ where
             .read_u32::<LittleEndian>()
             .map_err(|e| Error::read_error("Cannot read number of buckets", e))?;
 
-        let words = read_vocab_items(read, vocab_len as usize)?;
+        let words = read_vocab_items(read, vocab_len)?;
 
         Ok(SubwordVocab::new(
             words,
diff --git a/src/chunks/vocab/wrappers.rs b/src/chunks/vocab/wrappers.rs
index e9563b6..4df6527 100644
--- a/src/chunks/vocab/wrappers.rs
+++ b/src/chunks/vocab/wrappers.rs
@@ -1,4 +1,3 @@
-use std::convert::TryFrom;
 use std::io::{Read, Seek, SeekFrom, Write};
 
 use byteorder::{LittleEndian, ReadBytesExt};
@@ -110,7 +109,7 @@ impl ReadChunk for VocabWrap {
         R: Read + Seek,
     {
         let chunk_start_pos = read
-            .seek(SeekFrom::Current(0))
+            .stream_position()
             .map_err(|e| Error::read_error("Cannot get vocabulary chunk start position", e))?;
         let chunk_id = read
             .read_u32::<LittleEndian>()
diff --git a/src/compat/fasttext/io.rs b/src/compat/fasttext/io.rs
index 560c92a..6706df5 100644
--- a/src/compat/fasttext/io.rs
+++ b/src/compat/fasttext/io.rs
@@ -1,11 +1,10 @@
-use std::convert::TryInto;
 use std::io::{BufRead, Write};
 use std::ops::Mul;
 
 use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
 use ndarray::{s, Array2, ErrorKind as ShapeErrorKind, ShapeError};
 use serde::Serialize;
-use toml::Value;
+use toml::Table;
 
 use crate::chunks::metadata::Metadata;
 use crate::chunks::norms::NdNorms;
@@ -107,7 +106,7 @@ impl ReadFastTextPrivate for Embeddings<FastTextSubwordVocab, NdArray> {
             )));
         }
 
-        let metadata = Value::try_from(config).map_err(|e| {
+        let metadata = Table::try_from(config).map_err(|e| {
             Error::Format(format!("Cannot serialize model metadata to TOML: {}", e))
         })?;
 
diff --git a/src/similarity.rs b/src/similarity.rs
index e594850..67f246f 100644
--- a/src/similarity.rs
+++ b/src/similarity.rs
@@ -362,7 +362,7 @@ where
 
 #[cfg(test)]
 mod tests {
-
+    use std::f32;
     use std::fs::File;
     use std::io::BufReader;
 
@@ -482,7 +482,7 @@ mod tests {
         .abs_diff_eq(&1f32, 1e-5));
         assert!((WordSimilarityResult {
             word: "test",
-            similarity: NotNan::new(0.70710678).unwrap()
+            similarity: NotNan::new(f32::consts::FRAC_1_SQRT_2).unwrap()
         })
         .angular_similarity()
         .abs_diff_eq(&0.75, 1e-5));
@@ -510,7 +510,7 @@ mod tests {
         .abs_diff_eq(&0f32, 1e-5));
         assert!((WordSimilarityResult {
             word: "test",
-            similarity: NotNan::new(0.70710678).unwrap()
+            similarity: NotNan::new(f32::consts::FRAC_1_SQRT_2).unwrap()
         })
         .euclidean_distance()
         .abs_diff_eq(&0.76537, 1e-5));
@@ -538,7 +538,7 @@ mod tests {
         .abs_diff_eq(&1f32, 1e-5));
         assert!((WordSimilarityResult {
             word: "test",
-            similarity: NotNan::new(0.70710678).unwrap()
+            similarity: NotNan::new(f32::consts::FRAC_1_SQRT_2).unwrap()
         })
         .euclidean_similarity()
         .abs_diff_eq(&0.61732, 1e-5));
@@ -602,7 +602,7 @@ mod tests {
         assert_eq!(10, result.len());
         assert_eq!(result.next().unwrap().word, "Berlin");
 
-        for (idx, word_similarity) in result.into_iter().enumerate() {
+        for (idx, word_similarity) in result.enumerate() {
             assert_eq!(SIMILARITY_ORDER[idx], word_similarity.word)
         }
     }
diff --git a/src/subword.rs b/src/subword.rs
index 6d1c326..4a91502 100644
--- a/src/subword.rs
+++ b/src/subword.rs
@@ -86,17 +86,13 @@ where
     }
 
     fn buckets(&self) -> usize {
-        self.buckets_exp as usize
+        self.buckets_exp
     }
 }
 
 impl<H> Clone for HashIndexer<H> {
     fn clone(&self) -> Self {
-        HashIndexer {
-            buckets_exp: self.buckets_exp,
-            mask: self.mask,
-            _phantom: PhantomData,
-        }
+        *self
     }
 }
 
@@ -699,8 +695,7 @@ mod tests {
                 .subword_indices_with_ngrams(3, 6, &indexer)
                 .collect::<Vec<_>>();
             ngrams_indices_test.sort_by_key(|ngrams_indices_pairs| ngrams_indices_pairs.1.clone());
-            for (iter_check, iter_test) in ngrams_indices_check.into_iter().zip(ngrams_indices_test)
-            {
+            for (iter_check, iter_test) in ngrams_indices_check.iter().zip(ngrams_indices_test) {
                 assert_eq!(iter_check.0, iter_test.0);
             }
         }
diff --git a/src/util.rs b/src/util.rs
index 63f7f20..30e8f7f 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -20,7 +20,7 @@ impl<T> FromIteratorWithCapacity<T> for Vec<T> {
         I: IntoIterator<Item = T>,
     {
         let mut v = Vec::with_capacity(capacity);
-        v.extend(iter.into_iter());
+        v.extend(iter);
         v
     }
 }
@@ -31,7 +31,7 @@ impl<T> FromIteratorWithCapacity<T> for VecDeque<T> {
         I: IntoIterator<Item = T>,
     {
         let mut v = VecDeque::with_capacity(capacity);
-        v.extend(iter.into_iter());
+        v.extend(iter);
         v
     }
 }