diff --git a/src/client/async.rs b/src/client/async.rs
index 8f59c5a2..03dca9ed 100644
--- a/src/client/async.rs
+++ b/src/client/async.rs
@@ -205,6 +205,12 @@ impl Client {
                 HeaderValue::from_str(account).unwrap(),
             );
         }
+        if let Some(key) = &self.headers.idempotency_key {
+            headers.insert(
+                HeaderName::from_static("idempotency-key"),
+                HeaderValue::from_str(key).unwrap(),
+            );
+        }
         if let Some(client_id) = &self.headers.client_id {
             headers.insert(
                 HeaderName::from_static("client-id"),
diff --git a/src/params.rs b/src/params.rs
index c4cac3e1..2b9ec32f 100644
--- a/src/params.rs
+++ b/src/params.rs
@@ -21,6 +21,7 @@ pub struct Headers {
     pub stripe_version: Option<ApiVersion>,
     pub stripe_account: Option<String>,
     pub user_agent: Option<String>,
+    pub idempotency_key: Option<String>,
 }
 
 /// Implemented by types which represent stripe objects.