diff --git a/src/client/conn.rs b/src/client/conn.rs
index 91a8551705..6746f441e7 100644
--- a/src/client/conn.rs
+++ b/src/client/conn.rs
@@ -560,6 +560,7 @@ impl Builder {
             h1_parser_config: Default::default(),
             h1_title_case_headers: false,
             h1_preserve_header_case: false,
+            #[cfg(feature = "ffi")]
             h1_preserve_header_order: false,
             h1_max_buf_size: None,
             #[cfg(feature = "ffi")]
@@ -966,9 +967,11 @@ impl Builder {
                     if opts.h1_title_case_headers {
                         conn.set_title_case_headers();
                     }
+                    #[cfg(feature = "ffi")]
                     if opts.h1_preserve_header_case {
                         conn.set_preserve_header_case();
                     }
+                    #[cfg(feature = "ffi")]
                     if opts.h1_preserve_header_order {
                         conn.set_preserve_header_order();
                     }
diff --git a/src/ext.rs b/src/ext.rs
index 59a01ca964..863e83f682 100644
--- a/src/ext.rs
+++ b/src/ext.rs
@@ -5,6 +5,7 @@ use http::header::HeaderName;
 #[cfg(feature = "http1")]
 use http::header::{IntoHeaderName, ValueIter};
 use http::HeaderMap;
+#[cfg(feature = "ffi")]
 use std::collections::HashMap;
 #[cfg(feature = "http2")]
 use std::fmt;
@@ -123,6 +124,7 @@ impl HeaderCaseMap {
     }
 }
 
+#[cfg(feature = "ffi")]
 #[derive(Clone, Debug)]
 /// Hashmap<Headername, numheaders with that name>
 pub(crate) struct OriginalHeaderOrder {
diff --git a/src/proto/h1/role.rs b/src/proto/h1/role.rs
index 4c933f42ed..b2e885a217 100644
--- a/src/proto/h1/role.rs
+++ b/src/proto/h1/role.rs
@@ -16,7 +16,9 @@ use crate::body::DecodedLength;
 #[cfg(feature = "server")]
 use crate::common::date;
 use crate::error::Parse;
-use crate::ext::{HeaderCaseMap, OriginalHeaderOrder};
+use crate::ext::HeaderCaseMap;
+#[cfg(feature = "ffi")]
+use crate::ext::OriginalHeaderOrder;
 use crate::headers;
 use crate::proto::h1::{
     Encode, Encoder, Http1Transaction, ParseContext, ParseResult, ParsedMessage,
@@ -316,6 +318,7 @@ impl Http1Transaction for Server {
             extensions.insert(header_case_map);
         }
 
+        #[cfg(feature = "ffi")]
         if let Some(header_order) = header_order {
             extensions.insert(header_order);
         }
@@ -1043,6 +1046,7 @@ impl Http1Transaction for Client {
                 extensions.insert(header_case_map);
             }
 
+            #[cfg(feature = "ffi")]
             if let Some(header_order) = header_order {
                 extensions.insert(header_order);
             }