diff --git a/dotenv/Cargo.toml b/dotenv/Cargo.toml
index 4c2fb5a..317921b 100644
--- a/dotenv/Cargo.toml
+++ b/dotenv/Cargo.toml
@@ -16,17 +16,17 @@ readme = "../README.md"
 keywords = ["environment", "env", "dotenv", "settings", "config"]
 license = "MIT"
 repository = "https://github.com/dotenv-rs/dotenv"
-edition = "2018"
+edition = "2021"
 
 [[bin]]
 name = "dotenv"
 required-features = ["cli"]
 
 [dependencies]
-clap = { version = "2", optional = true }
+clap = { version = "3.0.6", optional = true }
 
 [dev-dependencies]
-tempfile = "3.0.0"
+tempfile = "3.3.0"
 
 [features]
 cli = ["clap"]
diff --git a/dotenv/src/bin/dotenv.rs b/dotenv/src/bin/dotenv.rs
index dce09c6..9a0aff5 100644
--- a/dotenv/src/bin/dotenv.rs
+++ b/dotenv/src/bin/dotenv.rs
@@ -29,13 +29,12 @@ fn make_command(name: &str, args: Vec<&str>) -> Command {
 fn main() {
     let matches = App::new("dotenv")
         .about("Run a command using the environment in a .env file")
-        .usage("dotenv <COMMAND> [ARGS]...")
+        .override_usage("dotenv <COMMAND> [ARGS]...")
         .setting(AppSettings::AllowExternalSubcommands)
         .setting(AppSettings::ArgRequiredElseHelp)
-        .setting(AppSettings::UnifiedHelpMessage)
         .arg(
-            Arg::with_name("FILE")
-                .short("f")
+            Arg::new("FILE")
+                .short('f')
                 .long("file")
                 .takes_value(true)
                 .help("Use a specific .env file (defaults to .env)"),
@@ -49,7 +48,7 @@ fn main() {
     .unwrap_or_else(|e| die!("error: failed to load environment: {}", e));
 
     let mut command = match matches.subcommand() {
-        (name, Some(matches)) => {
+        Some((name, matches)) => {
             let args = matches
                 .values_of("")
                 .map(|v| v.collect())
diff --git a/dotenv/src/lib.rs b/dotenv/src/lib.rs
index f2b1b0a..9beb336 100644
--- a/dotenv/src/lib.rs
+++ b/dotenv/src/lib.rs
@@ -4,6 +4,7 @@
 //! variables is not practical. It loads environment variables from a .env
 //! file, if available, and mashes those with the actual environment variables
 //! provided by the operating system.
+#![forbid(unsafe_code)]
 
 mod errors;
 mod find;
diff --git a/dotenv_codegen/Cargo.toml b/dotenv_codegen/Cargo.toml
index 5227f0d..f3aae8a 100644
--- a/dotenv_codegen/Cargo.toml
+++ b/dotenv_codegen/Cargo.toml
@@ -15,8 +15,8 @@ license = "MIT"
 homepage = "https://github.com/dotenv-rs/dotenv"
 repository = "https://github.com/dotenv-rs/dotenv"
 description = "A `dotenv` implementation for Rust"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
-dotenv_codegen_implementation = { version = "0.15", path = "../dotenv_codegen_implementation" }
-proc-macro-hack = "0.5"
+dotenv_codegen_implementation = { path = "../dotenv_codegen_implementation" }
+proc-macro-hack = "0.5.19"
diff --git a/dotenv_codegen/src/lib.rs b/dotenv_codegen/src/lib.rs
index c7588d4..459d344 100644
--- a/dotenv_codegen/src/lib.rs
+++ b/dotenv_codegen/src/lib.rs
@@ -1,3 +1,5 @@
+#![forbid(unsafe_code)]
+
 use proc_macro_hack::proc_macro_hack;
 
 #[proc_macro_hack]
diff --git a/dotenv_codegen_implementation/Cargo.toml b/dotenv_codegen_implementation/Cargo.toml
index 23b719b..f61a949 100644
--- a/dotenv_codegen_implementation/Cargo.toml
+++ b/dotenv_codegen_implementation/Cargo.toml
@@ -18,11 +18,11 @@ license = "MIT"
 homepage = "https://github.com/dotenv-rs/dotenv"
 repository = "https://github.com/dotenv-rs/dotenv"
 description = "A `dotenv` implementation for Rust"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
-proc-macro2 = "1"
-quote = "1"
-syn = "1"
-proc-macro-hack = "0.5"
-dotenv = { version = "0.15", path = "../dotenv" }
+proc-macro2 = "1.0.36"
+quote = "1.0.14"
+syn = "1.0.85"
+proc-macro-hack = "0.5.19"
+dotenv = { path = "../dotenv" }
diff --git a/dotenv_codegen_implementation/src/lib.rs b/dotenv_codegen_implementation/src/lib.rs
index 50a6cc2..0cee4d7 100644
--- a/dotenv_codegen_implementation/src/lib.rs
+++ b/dotenv_codegen_implementation/src/lib.rs
@@ -1,3 +1,5 @@
+#![forbid(unsafe_code)]
+
 extern crate proc_macro;
 
 use std::env::{self, VarError};