diff --git a/clippy.toml b/clippy.toml
new file mode 100644
index 00000000..dcec9d87
--- /dev/null
+++ b/clippy.toml
@@ -0,0 +1 @@
+too-many-arguments-threshold = 8
\ No newline at end of file
diff --git a/src/child.rs b/src/child.rs
index 6558ebdb..7246ef6e 100644
--- a/src/child.rs
+++ b/src/child.rs
@@ -41,7 +41,7 @@ pub fn new_command(program: &str) -> Command {
 /// given sender.
 fn read_and_send<R, F>(
     mut reader: R,
-    sender: mpsc::Sender<OutputFragment>,
+    sender: &mpsc::Sender<OutputFragment>,
     mut map: F,
 ) -> io::Result<()>
 where
@@ -104,10 +104,7 @@ where
             .rev()
             .find(|(_, ch)| *ch == b'\n')
         {
-            let next_in_progress: Vec<u8> = self.in_progress[last_newline + 1..]
-                .iter()
-                .cloned()
-                .collect();
+            let next_in_progress: Vec<u8> = self.in_progress[last_newline + 1..].to_vec();
             let mut these_lines = mem::replace(&mut self.in_progress, next_in_progress);
             these_lines.truncate(last_newline + 1);
             let these_lines = String::from_utf8(these_lines)?;
@@ -153,9 +150,9 @@ pub fn run(mut command: Command, command_name: &str) -> Result<String, Error> {
     // waiting on the child process.
 
     let stdout_handle =
-        thread::spawn(move || read_and_send(stdout, stdout_send, OutputFragment::Stdout));
+        thread::spawn(move || read_and_send(stdout, &stdout_send, OutputFragment::Stdout));
     let stderr_handle =
-        thread::spawn(move || read_and_send(stderr, stderr_send, OutputFragment::Stderr));
+        thread::spawn(move || read_and_send(stderr, &stderr_send, OutputFragment::Stderr));
 
     let mut stdout = OutputAccumulator::new(|line| {
         info!("{} (stdout): {}", command_name, line);
@@ -182,7 +179,7 @@ pub fn run(mut command: Command, command_name: &str) -> Result<String, Error> {
 
     let exit = child.wait()?;
     if exit.success() {
-        return Ok(stdout);
+        Ok(stdout)
     } else {
         drop((stdout, stderr));
         bail!("failed to execute `{}`: exited with {}", command_name, exit)
diff --git a/src/command/build.rs b/src/command/build.rs
index c6bad240..c55d55dd 100644
--- a/src/command/build.rs
+++ b/src/command/build.rs
@@ -220,7 +220,7 @@ impl Build {
         Ok(())
     }
 
-    fn get_process_steps(mode: &BuildMode) -> Vec<(&'static str, BuildStep)> {
+    fn get_process_steps(mode: BuildMode) -> Vec<(&'static str, BuildStep)> {
         macro_rules! steps {
             ($($name:ident),+) => {
                 {
diff --git a/src/command/login.rs b/src/command/login.rs
index 0ee09c3d..4c0aa942 100644
--- a/src/command/login.rs
+++ b/src/command/login.rs
@@ -5,11 +5,11 @@ use PBAR;
 
 pub fn login(
     registry: Option<String>,
-    scope: Option<String>,
+    scope: &Option<String>,
     always_auth: bool,
-    auth_type: Option<String>,
+    auth_type: &Option<String>,
 ) -> result::Result<(), failure::Error> {
-    let registry = registry.unwrap_or(npm::DEFAULT_NPM_REGISTRY.to_string());
+    let registry = registry.unwrap_or_else(|| npm::DEFAULT_NPM_REGISTRY.to_string());
 
     info!("Logging in to npm...");
     info!(
@@ -20,6 +20,6 @@ pub fn login(
     npm::npm_login(&registry, &scope, always_auth, &auth_type)?;
     info!("Logged you in!");
 
-    PBAR.message(&format!("👋  logged you in!"));
+    PBAR.message(&"👋  logged you in!".to_string());
     Ok(())
 }
diff --git a/src/command/mod.rs b/src/command/mod.rs
index 86a8235b..7259720e 100644
--- a/src/command/mod.rs
+++ b/src/command/mod.rs
@@ -90,7 +90,7 @@ pub enum Command {
 pub fn run_wasm_pack(command: Command) -> result::Result<(), Error> {
     // Run the correct command based off input and store the result of it so that we can clear
     // the progress bar then return it
-    let status = match command {
+    match command {
         Command::Build(build_opts) => {
             info!("Running build command...");
             Build::try_from_opts(build_opts).and_then(|mut b| b.run())
@@ -120,14 +120,11 @@ pub fn run_wasm_pack(command: Command) -> result::Result<(), Error> {
                 "Registry: {:?}, Scope: {:?}, Always Auth: {}, Auth Type: {:?}",
                 &registry, &scope, &always_auth, &auth_type
             );
-            login(registry, scope, always_auth, auth_type)
+            login(registry, &scope, always_auth, &auth_type)
         }
         Command::Test(test_opts) => {
             info!("Running test command...");
             Test::try_from_opts(test_opts).and_then(|t| t.run())
         }
-    };
-
-    // Return the actual status of the program to the main function
-    status
+    }
 }
diff --git a/src/command/publish/mod.rs b/src/command/publish/mod.rs
index 568104b4..f71fb534 100644
--- a/src/command/publish/mod.rs
+++ b/src/command/publish/mod.rs
@@ -15,7 +15,7 @@ use PBAR;
 /// Creates a tarball from a 'pkg' directory
 /// and publishes it to the NPM registry
 pub fn publish(
-    _target: String,
+    _target: &str,
     path: Option<PathBuf>,
     access: Option<Access>,
 ) -> result::Result<(), Error> {
diff --git a/src/command/utils.rs b/src/command/utils.rs
index f1711150..5a29a747 100644
--- a/src/command/utils.rs
+++ b/src/command/utils.rs
@@ -11,7 +11,7 @@ use PBAR;
 /// If an explicit path is given, then use it, otherwise assume the current
 /// directory is the crate path.
 pub fn set_crate_path(path: Option<PathBuf>) -> Result<PathBuf, failure::Error> {
-    Ok(path.unwrap_or(PathBuf::from(".")))
+    Ok(path.unwrap_or_else(|| PathBuf::from(".")))
 }
 
 /// Construct our `pkg` directory in the crate.
diff --git a/src/installer.rs b/src/installer.rs
index b2e42ad2..ce89667c 100644
--- a/src/installer.rs
+++ b/src/installer.rs
@@ -114,7 +114,7 @@ fn confirm_can_overwrite(dst: &Path) -> Result<(), failure::Error> {
         .read_line(&mut line)
         .with_context(|_| "failed to read stdin")?;
 
-    if line.starts_with("y") || line.starts_with("Y") {
+    if line.starts_with('y') || line.starts_with('Y') {
         return Ok(());
     }
 
diff --git a/src/lockfile.rs b/src/lockfile.rs
index d174f6a0..3edd6cff 100644
--- a/src/lockfile.rs
+++ b/src/lockfile.rs
@@ -1,5 +1,7 @@
 //! Reading Cargo.lock lock file.
 
+#![allow(clippy::new_ret_no_self)]
+
 use std::fs;
 use std::path::PathBuf;
 
diff --git a/src/manifest/mod.rs b/src/manifest/mod.rs
index 92f03cd4..0d8802a9 100644
--- a/src/manifest/mod.rs
+++ b/src/manifest/mod.rs
@@ -1,5 +1,7 @@
 //! Reading and writing Cargo.toml and package.json manifests.
 
+#![allow(clippy::new_ret_no_self, clippy::needless_pass_by_value)]
+
 mod npm;
 
 use std::fs;
@@ -20,7 +22,7 @@ use strsim::levenshtein;
 use toml;
 use PBAR;
 
-const WASM_PACK_METADATA_KEY: &'static str = "package.metadata.wasm-pack";
+const WASM_PACK_METADATA_KEY: &str = "package.metadata.wasm-pack";
 
 /// Store for metadata learned about a crate
 pub struct CrateData {
@@ -145,7 +147,7 @@ impl CargoWasmPackProfile {
         D: serde::Deserializer<'de>,
     {
         let mut profile = <Option<Self>>::deserialize(deserializer)?.unwrap_or_default();
-        profile.update_with_defaults(Self::default_dev());
+        profile.update_with_defaults(&Self::default_dev());
         Ok(profile)
     }
 
@@ -154,7 +156,7 @@ impl CargoWasmPackProfile {
         D: serde::Deserializer<'de>,
     {
         let mut profile = <Option<Self>>::deserialize(deserializer)?.unwrap_or_default();
-        profile.update_with_defaults(Self::default_release());
+        profile.update_with_defaults(&Self::default_release());
         Ok(profile)
     }
 
@@ -163,11 +165,11 @@ impl CargoWasmPackProfile {
         D: serde::Deserializer<'de>,
     {
         let mut profile = <Option<Self>>::deserialize(deserializer)?.unwrap_or_default();
-        profile.update_with_defaults(Self::default_profiling());
+        profile.update_with_defaults(&Self::default_profiling());
         Ok(profile)
     }
 
-    fn update_with_defaults(&mut self, defaults: Self) {
+    fn update_with_defaults(&mut self, defaults: &Self) {
         macro_rules! d {
             ( $( $path:ident ).* ) => {
                 self. $( $path ).* .get_or_insert(defaults. $( $path ).* .unwrap());
@@ -248,7 +250,7 @@ impl CrateData {
             for e in errors[..errors.len() - 1].iter().rev() {
                 err = err.context(e.to_string()).into();
             }
-            return err;
+            err
         }
     }
 
diff --git a/src/npm.rs b/src/npm.rs
index d99732fd..9ea2dcd9 100644
--- a/src/npm.rs
+++ b/src/npm.rs
@@ -6,7 +6,7 @@ use failure::{self, ResultExt};
 use log::info;
 
 /// The default npm registry used when we aren't working with a custom registry.
-pub const DEFAULT_NPM_REGISTRY: &'static str = "https://registry.npmjs.org/";
+pub const DEFAULT_NPM_REGISTRY: &str = "https://registry.npmjs.org/";
 
 /// Run the `npm pack` command.
 pub fn npm_pack(path: &str) -> Result<(), failure::Error> {
@@ -33,7 +33,7 @@ pub fn npm_publish(path: &str, access: Option<Access>) -> Result<(), failure::Er
 
 /// Run the `npm login` command.
 pub fn npm_login(
-    registry: &String,
+    registry: &str,
     scope: &Option<String>,
     always_auth: bool,
     auth_type: &Option<String>,
diff --git a/src/progressbar.rs b/src/progressbar.rs
index 24a89477..fa51cc65 100644
--- a/src/progressbar.rs
+++ b/src/progressbar.rs
@@ -75,7 +75,7 @@ impl ProgressOutput {
     }
 
     /// Add an error message.
-    pub fn error(&self, message: String) {
+    pub fn error(&self, message: &str) {
         let err = format!(
             "{} {}: {}",
             emoji::ERROR,
@@ -135,3 +135,9 @@ impl Drop for ProgressOutput {
         self.done();
     }
 }
+
+impl Default for ProgressOutput {
+    fn default() -> Self {
+        Self::new()
+    }
+}
diff --git a/src/readme.rs b/src/readme.rs
index 83a4b10c..2eec0608 100644
--- a/src/readme.rs
+++ b/src/readme.rs
@@ -23,8 +23,8 @@ pub fn copy_from_crate(path: &Path, out_dir: &Path, step: &Step) -> Result<(), f
     PBAR.step(step, &msg);
     let crate_readme_path = path.join("README.md");
     let new_readme_path = out_dir.join("README.md");
-    if let Err(_) = fs::copy(&crate_readme_path, &new_readme_path) {
+    if fs::copy(&crate_readme_path, &new_readme_path).is_err() {
         PBAR.warn("origin crate has no README");
-    };
+    }
     Ok(())
 }