diff --git a/src/transport.rs b/src/transport.rs
index 9571fdf..505e55a 100644
--- a/src/transport.rs
+++ b/src/transport.rs
@@ -177,6 +177,20 @@ impl<S: NekoSec> SendState<'_, S> {
     }
 }
 
+impl<S: NekoSec> zeroize::Zeroize for SendState<'_, S> {
+    fn zeroize(&mut self) {
+        self.counter.zeroize();
+    }
+}
+
+impl<S: NekoSec> Drop for SendState<'_, S> {
+    fn drop(&mut self) {
+        zeroize::Zeroize::zeroize(self);
+    }
+}
+
+impl<S: NekoSec> zeroize::ZeroizeOnDrop for SendState<'_, S> {}
+
 pub struct RecvState<'a, S: NekoSec> {
     transport: &'a AeadTransport<S>,
     counter: u64,
@@ -200,6 +214,20 @@ impl<S: NekoSec> RecvState<'_, S> {
     }
 }
 
+impl<S: NekoSec> zeroize::Zeroize for RecvState<'_, S> {
+    fn zeroize(&mut self) {
+        self.counter.zeroize();
+    }
+}
+
+impl<S: NekoSec> Drop for RecvState<'_, S> {
+    fn drop(&mut self) {
+        zeroize::Zeroize::zeroize(self);
+    }
+}
+
+impl<S: NekoSec> zeroize::ZeroizeOnDrop for RecvState<'_, S> {}
+
 #[cfg(test)]
 mod tests {
     use wharrgarbl_neko::{Neko128, Neko256};