diff --git a/src/apiversion.rs b/src/apiversion.rs
index d33d662..092610a 100644
--- a/src/apiversion.rs
+++ b/src/apiversion.rs
@@ -17,6 +17,7 @@
 use std::fmt;
 use std::str::FromStr;
 
+use reqwest::header::HeaderValue;
 use serde::de::{Error as DeserError, Visitor};
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
@@ -38,6 +39,12 @@ fn parse_component(component: &str, message: &str) -> Result<u16, Error> {
         .map_err(|_| Error::new(ErrorKind::InvalidResponse, message))
 }
 
+impl From<ApiVersion> for HeaderValue {
+    fn from(value: ApiVersion) -> HeaderValue {
+        value.to_string().parse().unwrap()
+    }
+}
+
 impl FromStr for ApiVersion {
     type Err = Error;
 
diff --git a/src/services.rs b/src/services.rs
index dab94fb..c296fae 100644
--- a/src/services.rs
+++ b/src/services.rs
@@ -14,7 +14,7 @@
 
 //! OpenStack service types.
 
-use reqwest::r#async::RequestBuilder;
+use reqwest::header::HeaderMap;
 
 use super::{ApiVersion, Error, ErrorKind};
 
@@ -28,14 +28,14 @@ pub trait ServiceType {
         true
     }
 
-    /// Update the request to include the API version headers.
+    /// Update the headers to include the API version headers.
     ///
     /// The default implementation fails with `IncompatibleApiVersion`.
     fn set_api_version_headers(
         &self,
-        _request: RequestBuilder,
+        _headers: &mut HeaderMap,
         _version: ApiVersion,
-    ) -> Result<RequestBuilder, Error> {
+    ) -> Result<(), Error> {
         Err(Error::new(
             ErrorKind::IncompatibleApiVersion,
             format!(
@@ -124,11 +124,12 @@ impl ServiceType for ComputeService {
 
     fn set_api_version_headers(
         &self,
-        request: RequestBuilder,
+        headers: &mut HeaderMap,
         version: ApiVersion,
-    ) -> Result<RequestBuilder, Error> {
+    ) -> Result<(), Error> {
         // TODO: new-style header support
-        Ok(request.header("x-openstack-nova-api-version", version.to_string()))
+        let _ = headers.insert("x-openstack-nova-api-version", version.into());
+        Ok(())
     }
 }
 
diff --git a/src/session.rs b/src/session.rs
index 239b0d6..9a9c50a 100644
--- a/src/session.rs
+++ b/src/session.rs
@@ -19,6 +19,7 @@ use std::sync::Arc;
 use futures::future;
 use futures::prelude::*;
 use log::{debug, trace};
+use reqwest::header::HeaderMap;
 use reqwest::r#async::{RequestBuilder, Response};
 use reqwest::{Method, Url};
 use serde::de::DeserializeOwned;
@@ -251,8 +252,9 @@ impl Session {
             })
             .and_then(move |mut builder| {
                 if let Some(version) = api_version {
-                    builder = match service.set_api_version_headers(builder, version) {
-                        Ok(builder) => builder,
+                    let mut headers = HeaderMap::new();
+                    match service.set_api_version_headers(&mut headers, version) {
+                        Ok(()) => builder = builder.headers(headers),
                         Err(err) => return future::err(err),
                     }
                 }