diff --git a/benches/benchmarks.rs b/benches/benchmarks.rs
index 90c4b94..3c07903 100644
--- a/benches/benchmarks.rs
+++ b/benches/benchmarks.rs
@@ -2,9 +2,9 @@ use async_std::{fs as afs, task};
 use std::fs::{self, File};
 use std::io::prelude::*;
 
-use cacache;
+
 use criterion::{black_box, criterion_group, criterion_main, Criterion};
-use tempfile;
+
 
 const NUM_REPEATS: usize = 10;
 
@@ -97,7 +97,7 @@ fn read_hash_many_sync(c: &mut Criterion) {
     c.bench_function("get::data_hash_many_sync", move |b| {
         b.iter(|| {
             for sri in sris.iter() {
-                cacache::read_hash_sync(black_box(&cache), black_box(&sri)).unwrap();
+                cacache::read_hash_sync(black_box(&cache), black_box(sri)).unwrap();
             }
         })
     });
@@ -138,7 +138,7 @@ fn read_hash_many_async(c: &mut Criterion) {
         b.iter(|| {
             let tasks = sris
                 .iter()
-                .map(|sri| cacache::read_hash(black_box(&cache), black_box(&sri)));
+                .map(|sri| cacache::read_hash(black_box(&cache), black_box(sri)));
             task::block_on(futures::future::join_all(tasks));
         })
     });
diff --git a/src/content/read.rs b/src/content/read.rs
index 6bd3913..ade2c97 100644
--- a/src/content/read.rs
+++ b/src/content/read.rs
@@ -53,7 +53,7 @@ impl AsyncReader {
 }
 
 pub fn open(cache: &Path, sri: Integrity) -> Result<Reader> {
-    let cpath = path::content_path(&cache, &sri);
+    let cpath = path::content_path(cache, &sri);
     Ok(Reader {
         fd: File::open(cpath).to_internal()?,
         checker: IntegrityChecker::new(sri),
@@ -61,7 +61,7 @@ pub fn open(cache: &Path, sri: Integrity) -> Result<Reader> {
 }
 
 pub async fn open_async(cache: &Path, sri: Integrity) -> Result<AsyncReader> {
-    let cpath = path::content_path(&cache, &sri);
+    let cpath = path::content_path(cache, &sri);
     Ok(AsyncReader {
         fd: async_std::fs::File::open(cpath).await.to_internal()?,
         checker: IntegrityChecker::new(sri),
@@ -69,21 +69,21 @@ pub async fn open_async(cache: &Path, sri: Integrity) -> Result<AsyncReader> {
 }
 
 pub fn read(cache: &Path, sri: &Integrity) -> Result<Vec<u8>> {
-    let cpath = path::content_path(&cache, &sri);
+    let cpath = path::content_path(cache, sri);
     let ret = fs::read(&cpath).to_internal()?;
     sri.check(&ret)?;
     Ok(ret)
 }
 
 pub async fn read_async<'a>(cache: &'a Path, sri: &'a Integrity) -> Result<Vec<u8>> {
-    let cpath = path::content_path(&cache, &sri);
+    let cpath = path::content_path(cache, sri);
     let ret = async_std::fs::read(&cpath).await.to_internal()?;
     sri.check(&ret)?;
     Ok(ret)
 }
 
 pub fn copy(cache: &Path, sri: &Integrity, to: &Path) -> Result<u64> {
-    let cpath = path::content_path(&cache, &sri);
+    let cpath = path::content_path(cache, sri);
     let ret = fs::copy(&cpath, to).to_internal()?;
     let data = fs::read(cpath).to_internal()?;
     sri.check(data)?;
@@ -91,7 +91,7 @@ pub fn copy(cache: &Path, sri: &Integrity, to: &Path) -> Result<u64> {
 }
 
 pub async fn copy_async<'a>(cache: &'a Path, sri: &'a Integrity, to: &'a Path) -> Result<u64> {
-    let cpath = path::content_path(&cache, &sri);
+    let cpath = path::content_path(cache, sri);
     let ret = async_std::fs::copy(&cpath, to).await.to_internal()?;
     let data = async_std::fs::read(cpath).await.to_internal()?;
     sri.check(data)?;
@@ -99,7 +99,7 @@ pub async fn copy_async<'a>(cache: &'a Path, sri: &'a Integrity, to: &'a Path) -
 }
 
 pub fn has_content(cache: &Path, sri: &Integrity) -> Option<Integrity> {
-    if path::content_path(&cache, &sri).exists() {
+    if path::content_path(cache, sri).exists() {
         Some(sri.clone())
     } else {
         None
@@ -107,7 +107,7 @@ pub fn has_content(cache: &Path, sri: &Integrity) -> Option<Integrity> {
 }
 
 pub async fn has_content_async(cache: &Path, sri: &Integrity) -> Option<Integrity> {
-    if async_std::fs::metadata(path::content_path(&cache, &sri))
+    if async_std::fs::metadata(path::content_path(cache, sri))
         .await
         .is_ok()
     {
diff --git a/src/content/rm.rs b/src/content/rm.rs
index 5b85f0d..7a60869 100644
--- a/src/content/rm.rs
+++ b/src/content/rm.rs
@@ -8,12 +8,12 @@ use crate::content::path;
 use crate::errors::{Internal, Result};
 
 pub fn rm(cache: &Path, sri: &Integrity) -> Result<()> {
-    fs::remove_file(path::content_path(&cache, &sri)).to_internal()?;
+    fs::remove_file(path::content_path(cache, sri)).to_internal()?;
     Ok(())
 }
 
 pub async fn rm_async(cache: &Path, sri: &Integrity) -> Result<()> {
-    afs::remove_file(path::content_path(&cache, &sri))
+    afs::remove_file(path::content_path(cache, sri))
         .await
         .to_internal()?;
     Ok(())
diff --git a/src/content/write.rs b/src/content/write.rs
index a6079d8..7861525 100644
--- a/src/content/write.rs
+++ b/src/content/write.rs
@@ -16,7 +16,7 @@ use tempfile::NamedTempFile;
 use crate::content::path;
 use crate::errors::{Internal, Result};
 
-pub const MAX_MMAP_SIZE: usize = 1 * 1024 * 1024;
+pub const MAX_MMAP_SIZE: usize = 1024 * 1024;
 
 pub struct Writer {
     cache: PathBuf,
@@ -73,12 +73,12 @@ impl Writer {
 
 impl Write for Writer {
     fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
-        self.builder.input(&buf);
+        self.builder.input(buf);
         if let Some(mmap) = &mut self.mmap {
-            mmap.copy_from_slice(&buf);
+            mmap.copy_from_slice(buf);
             Ok(buf.len())
         } else {
-            self.tmpfile.write(&buf)
+            self.tmpfile.write(buf)
         }
     }
 
@@ -216,7 +216,7 @@ impl AsyncWriter {
 
 impl AsyncWrite for AsyncWriter {
     fn poll_write(
-        mut self: Pin<&mut Self>,
+        self: Pin<&mut Self>,
         cx: &mut Context<'_>,
         buf: &[u8],
     ) -> Poll<std::io::Result<usize>> {
@@ -273,7 +273,7 @@ impl AsyncWrite for AsyncWriter {
         }
     }
 
-    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
+    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
         let state = &mut *self.0.lock().unwrap();
 
         loop {
@@ -313,7 +313,7 @@ impl AsyncWrite for AsyncWriter {
         }
     }
 
-    fn poll_close(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
+    fn poll_close(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<()>> {
         let state = &mut *self.0.lock().unwrap();
 
         loop {
diff --git a/src/get.rs b/src/get.rs
index 625ab0d..178bc34 100644
--- a/src/get.rs
+++ b/src/get.rs
@@ -86,10 +86,10 @@ impl Reader {
         if let Some(entry) = index::find_async(cache.as_ref(), key.as_ref()).await? {
             Reader::open_hash(cache, entry.integrity).await
         } else {
-            Err(Error::EntryNotFound(
+            return Err(Error::EntryNotFound(
                 cache.as_ref().to_path_buf(),
                 key.as_ref().into(),
-            ))?
+            ))
         }
     }
 
@@ -143,10 +143,10 @@ where
     if let Some(entry) = index::find_async(cache.as_ref(), key.as_ref()).await? {
         read_hash(cache, &entry.integrity).await
     } else {
-        Err(Error::EntryNotFound(
+        return Err(Error::EntryNotFound(
             cache.as_ref().to_path_buf(),
             key.as_ref().into(),
-        ))?
+        ))
     }
 }
 
@@ -195,10 +195,10 @@ where
     if let Some(entry) = index::find_async(cache.as_ref(), key.as_ref()).await? {
         copy_hash(cache, &entry.integrity, to).await
     } else {
-        Err(Error::EntryNotFound(
+        return Err(Error::EntryNotFound(
             cache.as_ref().to_path_buf(),
             key.as_ref().into(),
-        ))?
+        ))
     }
 }
 
@@ -240,7 +240,7 @@ where
 
 /// Returns true if the given hash exists in the cache.
 pub async fn exists<P: AsRef<Path>>(cache: P, sri: &Integrity) -> bool {
-    read::has_content_async(cache.as_ref(), &sri)
+    read::has_content_async(cache.as_ref(), sri)
         .await
         .is_some()
 }
@@ -310,10 +310,10 @@ impl SyncReader {
         if let Some(entry) = index::find(cache.as_ref(), key.as_ref())? {
             SyncReader::open_hash(cache, entry.integrity)
         } else {
-            Err(Error::EntryNotFound(
+            return Err(Error::EntryNotFound(
                 cache.as_ref().to_path_buf(),
                 key.as_ref().into(),
-            ))?
+            ))
         }
     }
 
@@ -363,10 +363,10 @@ where
     if let Some(entry) = index::find(cache.as_ref(), key.as_ref())? {
         read_hash_sync(cache, &entry.integrity)
     } else {
-        Err(Error::EntryNotFound(
+        return Err(Error::EntryNotFound(
             cache.as_ref().to_path_buf(),
             key.as_ref().into(),
-        ))?
+        ))
     }
 }
 
@@ -387,7 +387,7 @@ pub fn read_hash_sync<P>(cache: P, sri: &Integrity) -> Result<Vec<u8>>
 where
     P: AsRef<Path>,
 {
-    Ok(read::read(cache.as_ref(), sri)?)
+    read::read(cache.as_ref(), sri)
 }
 
 /// Copies a cache entry by key to a specified location. Returns the number of
@@ -411,10 +411,10 @@ where
     if let Some(entry) = index::find(cache.as_ref(), key.as_ref())? {
         copy_hash_sync(cache, &entry.integrity, to)
     } else {
-        Err(Error::EntryNotFound(
+        return Err(Error::EntryNotFound(
             cache.as_ref().to_path_buf(),
             key.as_ref().into(),
-        ))?
+        ))
     }
 }
 
@@ -449,21 +449,19 @@ where
     P: AsRef<Path>,
     K: AsRef<str>,
 {
-    Ok(index::find(cache.as_ref(), key.as_ref())?)
+    index::find(cache.as_ref(), key.as_ref())
 }
 
 /// Returns true if the given hash exists in the cache.
 pub fn exists_sync<P: AsRef<Path>>(cache: P, sri: &Integrity) -> bool {
-    read::has_content(cache.as_ref(), &sri).is_some()
+    read::has_content(cache.as_ref(), sri).is_some()
 }
 
 #[cfg(test)]
 mod tests {
-    use async_attributes;
     use async_std::fs as afs;
     use async_std::prelude::*;
     use std::fs;
-    use tempfile;
 
     #[async_attributes::test]
     async fn test_open() {
diff --git a/src/index.rs b/src/index.rs
index 21bace8..3963973 100644
--- a/src/index.rs
+++ b/src/index.rs
@@ -11,9 +11,8 @@ use digest::Digest;
 use either::{Left, Right};
 use futures::io::{AsyncBufReadExt, AsyncWriteExt};
 use futures::stream::StreamExt;
-use hex;
 use serde_derive::{Deserialize, Serialize};
-use serde_json::{json, Value};
+use serde_json::Value;
 use sha1::Sha1;
 use sha2::Sha256;
 use ssri::Integrity;
@@ -63,7 +62,7 @@ impl Hash for SerializableMetadata {
 }
 
 pub fn insert(cache: &Path, key: &str, opts: WriteOpts) -> Result<Integrity> {
-    let bucket = bucket_path(&cache, &key);
+    let bucket = bucket_path(cache, key);
     fs::create_dir_all(bucket.parent().unwrap()).with_context(|| {
         format!(
             "Failed to create index bucket directory: {:?}",
@@ -75,7 +74,7 @@ pub fn insert(cache: &Path, key: &str, opts: WriteOpts) -> Result<Integrity> {
         integrity: opts.sri.clone().map(|x| x.to_string()),
         time: opts.time.unwrap_or_else(now),
         size: opts.size.unwrap_or(0),
-        metadata: opts.metadata.unwrap_or_else(|| json!(null)),
+        metadata: opts.metadata.unwrap_or(serde_json::Value::Null),
     })
     .with_context(|| format!("Failed to serialize entry with key `{}`", key))?;
 
@@ -97,7 +96,7 @@ pub fn insert(cache: &Path, key: &str, opts: WriteOpts) -> Result<Integrity> {
 }
 
 pub async fn insert_async<'a>(cache: &'a Path, key: &'a str, opts: WriteOpts) -> Result<Integrity> {
-    let bucket = bucket_path(&cache, &key);
+    let bucket = bucket_path(cache, key);
     afs::create_dir_all(bucket.parent().unwrap())
         .await
         .with_context(|| {
@@ -111,7 +110,7 @@ pub async fn insert_async<'a>(cache: &'a Path, key: &'a str, opts: WriteOpts) ->
         integrity: opts.sri.clone().map(|x| x.to_string()),
         time: opts.time.unwrap_or_else(now),
         size: opts.size.unwrap_or(0),
-        metadata: opts.metadata.unwrap_or_else(|| json!(null)),
+        metadata: opts.metadata.unwrap_or(serde_json::Value::Null),
     })
     .with_context(|| format!("Failed to serialize entry with key `{}`", key))?;
 
@@ -136,7 +135,7 @@ pub async fn insert_async<'a>(cache: &'a Path, key: &'a str, opts: WriteOpts) ->
 }
 
 pub fn find(cache: &Path, key: &str) -> Result<Option<Metadata>> {
-    let bucket = bucket_path(cache, &key);
+    let bucket = bucket_path(cache, key);
     Ok(bucket_entries(&bucket)
         .with_context(|| format!("Failed to read index bucket entries from {:?}", bucket))?
         .into_iter()
@@ -164,7 +163,7 @@ pub fn find(cache: &Path, key: &str) -> Result<Option<Metadata>> {
 }
 
 pub async fn find_async(cache: &Path, key: &str) -> Result<Option<Metadata>> {
-    let bucket = bucket_path(cache, &key);
+    let bucket = bucket_path(cache, key);
     Ok(bucket_entries_async(&bucket)
         .await
         .with_context(|| format!("Failed to read index bucket entries from {:?}", bucket))?
@@ -258,7 +257,7 @@ pub fn ls(cache: &Path) -> impl Iterator<Item = Result<Metadata>> {
 }
 
 fn bucket_path(cache: &Path, key: &str) -> PathBuf {
-    let hashed = hash_key(&key);
+    let hashed = hash_key(key);
     cache
         .join(format!("index-v{}", INDEX_VERSION))
         .join(&hashed[0..2])
@@ -343,7 +342,7 @@ async fn bucket_entries_async(bucket: &Path) -> InternalResult<Vec<SerializableM
 mod tests {
     use super::*;
     use async_std::task;
-    use tempfile;
+    use serde_json::json;
 
     const MOCK_ENTRY: &str = "\n251d18a2b33264ea8655695fd23c88bd874cdea2c3dc9d8f9b7596717ad30fec\t{\"key\":\"hello\",\"integrity\":\"sha1-deadbeef\",\"time\":1234567,\"size\":0,\"metadata\":null}";
 
diff --git a/src/ls.rs b/src/ls.rs
index 408f43e..9ca40fa 100644
--- a/src/ls.rs
+++ b/src/ls.rs
@@ -12,7 +12,6 @@ pub fn list_sync<P: AsRef<Path>>(cache: P) -> impl Iterator<Item = Result<index:
 #[cfg(test)]
 mod tests {
     use super::*;
-    use tempfile;
 
     #[test]
     fn test_list_sync() {
diff --git a/src/put.rs b/src/put.rs
index cfaf962..ec5ec2d 100644
--- a/src/put.rs
+++ b/src/put.rs
@@ -144,7 +144,7 @@ impl Writer {
         let writer_sri = self.writer.close().await?;
         if let Some(sri) = &self.opts.sri {
             if sri.matches(&writer_sri).is_none() {
-                return Err(ssri::Error::IntegrityCheckError(sri.clone(), writer_sri))?;
+                return Err(ssri::Error::IntegrityCheckError(sri.clone(), writer_sri).into());
             }
         } else {
             self.opts.sri = Some(writer_sri.clone());
@@ -403,14 +403,14 @@ impl SyncWriter {
         let writer_sri = self.writer.close()?;
         if let Some(sri) = &self.opts.sri {
             if sri.matches(&writer_sri).is_none() {
-                return Err(ssri::Error::IntegrityCheckError(sri.clone(), writer_sri))?;
+                return Err(ssri::Error::IntegrityCheckError(sri.clone(), writer_sri).into());
             }
         } else {
             self.opts.sri = Some(writer_sri.clone());
         }
         if let Some(size) = self.opts.size {
             if size != self.written {
-                return Err(Error::SizeError(size, self.written))?;
+                return Err(Error::SizeError(size, self.written));
             }
         }
         if let Some(key) = self.key {
@@ -423,8 +423,6 @@ impl SyncWriter {
 
 #[cfg(test)]
 mod tests {
-    use async_attributes;
-
     #[async_attributes::test]
     async fn round_trip() {
         let tmp = tempfile::tempdir().unwrap();
diff --git a/src/rm.rs b/src/rm.rs
index 675a15b..968c3b0 100644
--- a/src/rm.rs
+++ b/src/rm.rs
@@ -66,7 +66,7 @@ where
 /// }
 /// ```
 pub async fn remove_hash<P: AsRef<Path>>(cache: P, sri: &Integrity) -> Result<()> {
-    Ok(rm::rm_async(cache.as_ref(), &sri).await?)
+    Ok(rm::rm_async(cache.as_ref(), sri).await?)
 }
 
 /// Removes entire contents of the cache, including temporary files, the entry
@@ -92,10 +92,8 @@ pub async fn remove_hash<P: AsRef<Path>>(cache: P, sri: &Integrity) -> Result<()
 /// }
 /// ```
 pub async fn clear<P: AsRef<Path>>(cache: P) -> Result<()> {
-    for entry in cache.as_ref().read_dir().to_internal()? {
-        if let Ok(entry) = entry {
-            afs::remove_dir_all(entry.path()).await.to_internal()?;
-        }
+    for entry in (cache.as_ref().read_dir().to_internal()?).flatten() {
+        afs::remove_dir_all(entry.path()).await.to_internal()?;
     }
     Ok(())
 }
@@ -152,7 +150,7 @@ where
 /// }
 /// ```
 pub fn remove_hash_sync<P: AsRef<Path>>(cache: P, sri: &Integrity) -> Result<()> {
-    Ok(rm::rm(cache.as_ref(), &sri)?)
+    rm::rm(cache.as_ref(), sri)
 }
 
 /// Removes entire contents of the cache synchronously, including temporary
@@ -176,10 +174,8 @@ pub fn remove_hash_sync<P: AsRef<Path>>(cache: P, sri: &Integrity) -> Result<()>
 /// }
 /// ```
 pub fn clear_sync<P: AsRef<Path>>(cache: P) -> Result<()> {
-    for entry in cache.as_ref().read_dir().to_internal()? {
-        if let Ok(entry) = entry {
-            fs::remove_dir_all(entry.path()).to_internal()?;
-        }
+    for entry in (cache.as_ref().read_dir().to_internal()?).flatten() {
+        fs::remove_dir_all(entry.path()).to_internal()?;
     }
     Ok(())
 }
@@ -201,7 +197,7 @@ mod tests {
             assert_eq!(entry, None);
 
             let data_exists = crate::exists(&dir, &sri).await;
-            assert_eq!(data_exists, true);
+            assert!(data_exists);
         });
     }
 
@@ -215,10 +211,10 @@ mod tests {
             crate::remove_hash(&dir, &sri).await.unwrap();
 
             let entry = crate::metadata(&dir, "key").await.unwrap();
-            assert_eq!(entry.is_some(), true);
+            assert!(entry.is_some());
 
             let data_exists = crate::exists(&dir, &sri).await;
-            assert_eq!(data_exists, false);
+            assert!(data_exists);
         });
     }
 
@@ -232,10 +228,10 @@ mod tests {
             crate::clear(&dir).await.unwrap();
 
             let entry = crate::metadata(&dir, "key").await.unwrap();
-            assert_eq!(entry.is_some(), false);
+            assert!(entry.is_some());
 
             let data_exists = crate::exists(&dir, &sri).await;
-            assert_eq!(data_exists, false);
+            assert!(data_exists);
         });
     }
 
@@ -251,7 +247,7 @@ mod tests {
         assert_eq!(new_entry, None);
 
         let data_exists = crate::exists_sync(&dir, &sri);
-        assert_eq!(data_exists, true);
+        assert!(data_exists);
     }
 
     #[test]
@@ -263,10 +259,10 @@ mod tests {
         crate::remove_hash_sync(&dir, &sri).unwrap();
 
         let entry = crate::metadata_sync(&dir, "key").unwrap();
-        assert_eq!(entry.is_some(), true);
+        assert!(entry.is_some());
 
         let data_exists = crate::exists_sync(&dir, &sri);
-        assert_eq!(data_exists, false);
+        assert!(data_exists);
     }
 
     #[test]
@@ -281,6 +277,6 @@ mod tests {
         assert_eq!(entry, None);
 
         let data_exists = crate::exists_sync(&dir, &sri);
-        assert_eq!(data_exists, false);
+        assert!(data_exists);
     }
 }