diff --git a/src/Client.ts b/src/Client.ts
index b049410e..98c97441 100644
--- a/src/Client.ts
+++ b/src/Client.ts
@@ -66,7 +66,7 @@ async function contextualize(
  * @param refId
  * @param cache A map to store the resolved refs
  * @param client The client instance
- * @param [signal] The `AbortSignal` if any
+ * @param requestOptions Only signal and headers are currently used if provided
  * @returns The resolved reference
  * @private
  */
@@ -74,15 +74,18 @@ function getRef(
     refId: string,
     cache: Record<string, any>,
     client: Client,
-    signal?: AbortSignal
+    requestOptions: RequestInit
 ): Promise<fhirclient.JsonObject> {
     if (!cache[refId]) {
 
+        const { signal, headers } = requestOptions;
+
         // Note that we set cache[refId] immediately! When the promise is
         // settled it will be updated. This is to avoid a ref being fetched
         // twice because some of these requests are executed in parallel.
         cache[refId] = client.request({
             url: refId,
+            headers,
             signal
         }).then(res => {
             cache[refId] = res;
@@ -106,7 +109,7 @@ function resolveRef(
     graph: boolean,
     cache: fhirclient.JsonObject,
     client: Client,
-    signal?: AbortSignal
+    requestOptions: fhirclient.RequestOptions
 ) {
     const node = getPath(obj, path);
     if (node) {
@@ -114,7 +117,7 @@ function resolveRef(
         return Promise.all(makeArray(node).filter(Boolean).map((item, i) => {
             const ref = item.reference;
             if (ref) {
-                return getRef(ref, cache, client, signal).then(sub => {
+                return getRef(ref, cache, client, requestOptions).then(sub => {
                     if (graph) {
                         if (isArray) {
                             if (path.indexOf("..") > -1) {
@@ -150,7 +153,7 @@ function resolveRefs(
     fhirOptions: fhirclient.FhirOptions,
     cache: fhirclient.JsonObject,
     client: Client,
-    signal?: AbortSignal
+    requestOptions: fhirclient.RequestOptions
 ) {
 
     // 1. Sanitize paths, remove any invalid ones
@@ -191,7 +194,7 @@ function resolveRefs(
     Object.keys(groups).sort().forEach(len => {
         const group = groups[len];
         task = task.then(() => Promise.all(group.map((path: string) => {
-            return resolveRef(obj, path, !!fhirOptions.graph, cache, client, signal);
+            return resolveRef(obj, path, !!fhirOptions.graph, cache, client, requestOptions);
         })));
     });
     return task;
@@ -898,7 +901,7 @@ export default class Client
                             options,
                             _resolvedRefs,
                             this,
-                            signal
+                            requestOptions
                         )));
                     }
                     else {
@@ -907,7 +910,7 @@ export default class Client
                             options,
                             _resolvedRefs,
                             this,
-                            signal
+                            requestOptions
                         );
                     }
 
diff --git a/src/types.d.ts b/src/types.d.ts
index da0a6449..209dc3dd 100644
--- a/src/types.d.ts
+++ b/src/types.d.ts
@@ -338,7 +338,7 @@ declare namespace fhirclient {
         /**
          * Supported PKCE Code challenge methods
          */
-         codeChallengeMethods: string[];
+        codeChallengeMethods: string[];
     }
 
     /**
diff --git a/test/Client.test.ts b/test/Client.test.ts
index a861ba5d..cc897996 100644
--- a/test/Client.test.ts
+++ b/test/Client.test.ts
@@ -1651,9 +1651,7 @@ describe("FHIR.client", () => {
 
         describe ("can resolve nested refs", () => {
             crossPlatformTest(async (env) => {
-                const client = new Client(env, {
-                    serverUrl: mockUrl
-                });
+                const client = new Client(env, { serverUrl: mockUrl });
 
                 // This is how the user had defined the list, If it works properly,
                 // the request function should resolve them in different order:
@@ -1665,49 +1663,57 @@ describe("FHIR.client", () => {
                     "encounter"
                 ];
 
+                function createHandler(json) {
+                    return function handler(req, res, next) {
+                        try {
+                            expect(req.headers['x-custom-header'], "Custom headers not sent on ref requests").to.equal('someCustomKey');
+                            res.json(json)
+                        } catch (ex) {
+                            next(ex)
+                        }
+                    }
+                }
+
                 // 1. Observation
                 // this request should be sent first!
                 mockServer.mock({
-                    headers: { "content-type": "application/json" },
-                    status: 200,
-                    body: {
+                    handler: createHandler({
                         resourceType: "Observation",
                         encounter: { reference: "encounter/1" },
                         subject: { reference: "subject/1" }
-                    }
+                    })
                 });
 
                 // 2. Patient (Observation.subject)
                 // this request should be sent second (even though it might
                 // reply after #3)
                 mockServer.mock({
-                    headers: { "content-type": "application/json" },
-                    status: 200,
-                    body: { resourceType: "Patient" }
+                    handler: createHandler({ resourceType: "Patient" })
                 });
 
                 // 3. Encounter
                 // this request should be sent third (even though it might
                 // reply before #2)
                 mockServer.mock({
-                    headers: { "content-type": "application/json" },
-                    status: 200,
-                    body: {
+                    handler: createHandler({
                         resourceType: "Encounter",
                         serviceProvider: { reference: "Organization/1" }
-                    }
+                    })
                 });
 
                 // 4. Organization (Encounter.serviceProvider)
                 // this request should be sent AFTER we have handled the response
                 // from #3!
                 mockServer.mock({
-                    headers: { "content-type": "application/json" },
-                    status: 200,
-                    body: { resourceType: "Organization" }
+                    handler: createHandler({ resourceType: "Organization" })
                 });
 
-                const result = await client.request("Observation/id", {
+                const result = await client.request({
+                    url: "Observation/id",
+                    headers: {
+                        'X-Custom-Header': 'someCustomKey',
+                    }
+                }, {
                     resolveReferences: refsToResolve
                 });