diff --git a/test-cargo-miri/src/main.rs b/test-cargo-miri/src/main.rs
index 9ec8e85887a7..c21547c29ff9 100644
--- a/test-cargo-miri/src/main.rs
+++ b/test-cargo-miri/src/main.rs
@@ -19,7 +19,9 @@ mod test {
     fn rng() {
         let mut rng = rand::rngs::StdRng::seed_from_u64(0xcafebeef);
         let x: u32 = rng.gen();
-        let y: u32 = rng.gen();
-        assert_ne!(x, y);
+        let y: usize = rng.gen();
+        let z: u128 = rng.gen();
+        assert_ne!(x as usize, y);
+        assert_ne!(y as u128, z);
     }
 }
diff --git a/test-cargo-miri/tests/test.rs b/test-cargo-miri/tests/test.rs
index ed9efa21e4fa..31425d5ad973 100644
--- a/test-cargo-miri/tests/test.rs
+++ b/test-cargo-miri/tests/test.rs
@@ -7,17 +7,19 @@ fn simple() {
     assert_eq!(4, 4);
 }
 
-// Having more than 1 test does seem to make a difference
-// (i.e., this calls ptr::swap which having just one test does not).
 #[test]
 fn entropy_rng() {
     // Use this opportunity to test querying the RNG (needs an external crate, hence tested here and not in the compiletest suite)
     let mut rng = SmallRng::from_entropy();
     let _val = rng.gen::<i32>();
+    let _val = rng.gen::<isize>();
+    let _val = rng.gen::<i128>();
 
     // Also try per-thread RNG.
     let mut rng = rand::thread_rng();
     let _val = rng.gen::<i32>();
+    let _val = rng.gen::<isize>();
+    let _val = rng.gen::<i128>();
 }
 
 // A test that won't work on miri