diff --git a/.github/workflows/CICD.yml b/.github/workflows/CICD.yml
index 220d97dd..d0b1aaea 100644
--- a/.github/workflows/CICD.yml
+++ b/.github/workflows/CICD.yml
@@ -27,11 +27,25 @@ jobs:
         toolchain: ${{ env.MIN_SUPPORTED_RUST_VERSION }}
         default: true
         profile: minimal # minimal component installation (ie, no documentation)
+        components: clippy, rustfmt
+
+    - name: Ensure `cargo fmt` has been run
+      uses: actions-rs/cargo@v1
+      with:
+        command: fmt
+        args: -- --check
+
+    - name: Run clippy (on minimum supported rust version to prevent warnings we can't fix)
+      uses: actions-rs/cargo@v1
+      with:
+        command: clippy
+        args: --locked --all-targets
 
     - name: Run tests
       uses: actions-rs/cargo@v1
       with:
         command: test
+        args: --locked
 
   build:
     name: ${{ matrix.job.os }} (${{ matrix.job.target }})
diff --git a/src/bin/hexyl.rs b/src/bin/hexyl.rs
index e57ca71c..367cc4e7 100644
--- a/src/bin/hexyl.rs
+++ b/src/bin/hexyl.rs
@@ -61,6 +61,7 @@ fn run() -> Result<(), AnyhowError> {
                 .short("l")
                 .takes_value(true)
                 .value_name("N")
+                .conflicts_with_all(&["length", "bytes"])
                 .hidden(true)
                 .help("Yet another alias for -n/--length"),
         )
@@ -304,9 +305,9 @@ impl NonNegativeI64 {
     }
 }
 
-impl Into<u64> for NonNegativeI64 {
-    fn into(self) -> u64 {
-        u64::try_from(self.0)
+impl From<NonNegativeI64> for u64 {
+    fn from(x: NonNegativeI64) -> u64 {
+        u64::try_from(x.0)
             .expect("invariant broken: NonNegativeI64 should contain a non-negative i64 value")
     }
 }
@@ -328,9 +329,9 @@ impl PositiveI64 {
     }
 }
 
-impl Into<u64> for PositiveI64 {
-    fn into(self) -> u64 {
-        u64::try_from(self.0)
+impl From<PositiveI64> for u64 {
+    fn from(x: PositiveI64) -> u64 {
+        u64::try_from(x.0)
             .expect("invariant broken: PositiveI64 should contain a positive i64 value")
     }
 }
@@ -357,9 +358,9 @@ impl Unit {
         match self {
             Self::Byte => 1,
             Self::Kilobyte => 1000,
-            Self::Megabyte => 1000_000,
-            Self::Gigabyte => 1000_000_000,
-            Self::Terabyte => 1000_000_000_000,
+            Self::Megabyte => 1_000_000,
+            Self::Gigabyte => 1_000_000_000,
+            Self::Terabyte => 1_000_000_000_000,
             Self::Kibibyte => 1 << 10,
             Self::Mebibyte => 1 << 20,
             Self::Gibibyte => 1 << 30,
diff --git a/tests/integration_tests.rs b/tests/integration_tests.rs
index 0508e532..bc718add 100644
--- a/tests/integration_tests.rs
+++ b/tests/integration_tests.rs
@@ -85,6 +85,30 @@ mod length {
             .assert()
             .failure();
     }
+
+    #[test]
+    fn fail_if_length_and_count_options_are_used_simultaneously() {
+        hexyl()
+            .arg("hello_world_elf64")
+            .arg("--length=32")
+            .arg("-l=10")
+            .assert()
+            .failure();
+    }
+}
+
+mod bytes {
+    use super::hexyl;
+
+    #[test]
+    fn fail_if_bytes_and_count_options_are_used_simultaneously() {
+        hexyl()
+            .arg("hello_world_elf64")
+            .arg("--bytes=32")
+            .arg("-l=10")
+            .assert()
+            .failure();
+    }
 }
 
 mod skip {