diff --git a/src/test.rs b/src/test.rs
index a7eb99f..6841f91 100644
--- a/src/test.rs
+++ b/src/test.rs
@@ -7,7 +7,7 @@ trait DebugExt: Debug {
     }
 }
 
-impl<T: Debug> DebugExt for T {}
+impl<T: Debug + ?Sized> DebugExt for T {}
 
 #[test]
 fn basic_push() {
@@ -120,4 +120,23 @@ fn iteration() {
         debugs.push(item.debug());
     }
     assert_eq!(debugs, ["1", "\"foo\"", "true"]);
+}
+
+#[test]
+fn zst() {
+    let vec: Vec<()> = vec![(), (), ()];
+
+    assert_eq!(vec[1], ());
+    for el in vec.iter() {
+        drop(el);
+    }
+    assert_eq!(vec.debug(), "[(), (), ()]");
+
+    let vec: Vec<dyn Debug> = vec![unsized: (), (), ()];
+
+    assert_eq!(vec[1].debug(), "()");
+    for el in vec.iter() {
+        drop(el);
+    }
+    assert_eq!(vec.debug(), "[(), (), ()]");
 }
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