diff --git a/cargo-miri-test/Cargo.toml b/cargo-miri-test/Cargo.toml
index 5fbe923f23d3..4fe009e025e1 100644
--- a/cargo-miri-test/Cargo.toml
+++ b/cargo-miri-test/Cargo.toml
@@ -2,6 +2,7 @@
 name = "cargo-miri-test"
 version = "0.1.0"
 authors = ["Oliver Schneider <git-spam-no-reply9815368754983@oli-obk.de>"]
+edition = "2018"
 
 [dependencies]
-byteorder = "1.0"
\ No newline at end of file
+byteorder = "1.0"
diff --git a/cargo-miri-test/src/main.rs b/cargo-miri-test/src/main.rs
index 4e1501dd57f2..1ae88a7db594 100644
--- a/cargo-miri-test/src/main.rs
+++ b/cargo-miri-test/src/main.rs
@@ -1,5 +1,3 @@
-extern crate byteorder;
-
 use byteorder::{BigEndian, ByteOrder};
 
 fn main() {
diff --git a/src/bin/cargo-miri.rs b/src/bin/cargo-miri.rs
index 69c4f122544a..da4a351368d3 100644
--- a/src/bin/cargo-miri.rs
+++ b/src/bin/cargo-miri.rs
@@ -46,11 +46,15 @@ fn main() {
     }
 
     if let Some("miri") = std::env::args().nth(1).as_ref().map(AsRef::as_ref) {
-        // this arm is when `cargo miri` is called
+        // this arm is when `cargo miri` is called.  We call `cargo rustc` for
+        // each applicable target, but with the RUSTC env var set to the `cargo-miri`
+        // binary so that we come back in the other branch, and dispatch
+        // the invocations to rustc and miri, respectively.
 
         let test = std::env::args().nth(2).map_or(false, |text| text == "test");
         let skip = if test { 3 } else { 2 };
 
+        // We need to get the manifest, and then the metadata, to enumerate targets.
         let manifest_path_arg = std::env::args().skip(skip).find(|val| {
             val.starts_with("--manifest-path=")
         });
@@ -92,6 +96,9 @@ fn main() {
             })
             .expect("could not find matching package");
         let package = metadata.packages.remove(package_index);
+
+        // Finally we got the metadata, iterate all targets and see for which ones
+        // we do anything.
         for target in package.targets {
             let args = std::env::args().skip(skip);
             let kind = target.kind.get(0).expect(
@@ -139,7 +146,8 @@ fn main() {
             }
         }
     } else {
-        // this arm is executed when cargo-miri runs `cargo rustc` with the `RUSTC` env var set to itself
+        // This arm is executed when cargo-miri runs `cargo rustc` with the `RUSTC` env var set to itself:
+        // Dependencies get dispatched to rustc, the final test/binary to miri.
 
         let home = option_env!("RUSTUP_HOME").or(option_env!("MULTIRUST_HOME"));
         let toolchain = option_env!("RUSTUP_TOOLCHAIN").or(option_env!("MULTIRUST_TOOLCHAIN"));