diff --git a/tests/e2e/api/src/http/axios/__tests__/utils.spec.ts b/tests/e2e/api/src/http/axios/__tests__/utils.spec.ts
index d7db9199e9a..88affd6d7e3 100644
--- a/tests/e2e/api/src/http/axios/__tests__/utils.spec.ts
+++ b/tests/e2e/api/src/http/axios/__tests__/utils.spec.ts
@@ -1,4 +1,4 @@
-import { buildURL } from '../utils';
+import { buildURL, buildURLWithParams } from '../utils';
 
 describe( 'buildURL', () => {
 	it( 'should use base when given no url', () => {
@@ -15,9 +15,16 @@ describe( 'buildURL', () => {
 		const url = buildURL( { baseURL: 'http://test.test', url: 'yes/test' } );
 		expect( url ).toBe( 'http://test.test/yes/test' );
 	} );
+} );
 
-	it( 'should combine base and url with trailing/leading slashes', () => {
-		const url = buildURL( { baseURL: 'http://test.test/////', url: '////yes/test' } );
-		expect( url ).toBe( 'http://test.test/yes/test' );
+describe( 'buildURLWithParams', () => {
+	it( 'should do nothing without query string', () => {
+		const url = buildURLWithParams( { baseURL: 'http://test.test' } );
+		expect( url ).toBe( 'http://test.test' );
+	} );
+
+	it( 'should append query string', () => {
+		const url = buildURLWithParams( { baseURL: 'http://test.test', params: { test: 'yes' } } );
+		expect( url ).toBe( 'http://test.test?test=yes' );
 	} );
 } );
diff --git a/tests/e2e/api/src/http/axios/axios-oauth-interceptor.ts b/tests/e2e/api/src/http/axios/axios-oauth-interceptor.ts
index cd7f6b12fe1..ff565d19170 100644
--- a/tests/e2e/api/src/http/axios/axios-oauth-interceptor.ts
+++ b/tests/e2e/api/src/http/axios/axios-oauth-interceptor.ts
@@ -2,10 +2,10 @@ import type { AxiosRequestConfig } from 'axios';
 import * as createHmac from 'create-hmac';
 import * as OAuth from 'oauth-1.0a';
 import { AxiosInterceptor } from './axios-interceptor';
-import { buildURL } from './utils';
+import { buildURLWithParams } from './utils';
 
 /**
- * A utility class for managing the lifecycle of an authentication interceptor.
+ * An interceptor for adding OAuth 1.0a signatures to HTTP requests.
  */
 export class AxiosOAuthInterceptor extends AxiosInterceptor {
 	/**
@@ -14,7 +14,7 @@ export class AxiosOAuthInterceptor extends AxiosInterceptor {
 	 * @type {Object}
 	 * @private
 	 */
-	private oauth: OAuth;
+	private readonly oauth: OAuth;
 
 	/**
 	 * Creates a new interceptor.
@@ -44,7 +44,7 @@ export class AxiosOAuthInterceptor extends AxiosInterceptor {
 	 * @return {AxiosRequestConfig} The request with the additional authorization headers.
 	 */
 	protected handleRequest( request: AxiosRequestConfig ): AxiosRequestConfig {
-		const url = buildURL( request );
+		const url = buildURLWithParams( request );
 		if ( url.startsWith( 'https' ) ) {
 			request.auth = {
 				username: this.oauth.consumer.key,
diff --git a/tests/e2e/api/src/http/axios/axios-response-interceptor.ts b/tests/e2e/api/src/http/axios/axios-response-interceptor.ts
index b936affe973..00c94459203 100644
--- a/tests/e2e/api/src/http/axios/axios-response-interceptor.ts
+++ b/tests/e2e/api/src/http/axios/axios-response-interceptor.ts
@@ -2,6 +2,9 @@ import { AxiosResponse } from 'axios';
 import { AxiosInterceptor } from './axios-interceptor';
 import { HTTPResponse } from '../http-client';
 
+/**
+ * An interceptor for transforming the responses from axios into a consistent format for package consumers.
+ */
 export class AxiosResponseInterceptor extends AxiosInterceptor {
 	/**
 	 * Transforms the Axios response into our HTTP response.
diff --git a/tests/e2e/api/src/http/axios/utils.ts b/tests/e2e/api/src/http/axios/utils.ts
index 4f6e5aa6ac8..09248825510 100644
--- a/tests/e2e/api/src/http/axios/utils.ts
+++ b/tests/e2e/api/src/http/axios/utils.ts
@@ -1,5 +1,10 @@
 import { AxiosRequestConfig } from 'axios';
 
+// @ts-ignore
+import buildFullPath = require( 'axios/lib/core/buildFullPath' );
+// @ts-ignore
+import appendParams = require( 'axios/lib/helpers/buildURL' );
+
 /**
  * Given an Axios request config this function generates the URL that Axios will
  * use to make the request.
@@ -8,17 +13,16 @@ import { AxiosRequestConfig } from 'axios';
  * @return {string} The merged URL.
  */
 export function buildURL( request: AxiosRequestConfig ): string {
-	const base = request.baseURL || '';
-	if ( ! request.url ) {
-		return base;
-	}
-
-	// Axios ignores the base when the URL is absolute.
-	const url = request.url;
-	if ( ! base || url.match( /^([a-z][a-z\d+\-.]*:)?\/\/[^\/]/i ) ) {
-		return url;
-	}
-
-	// Remove trailing slashes from the base and leading slashes from the URL so we can combine them consistently.
-	return base.replace( /\/+$/, '' ) + '/' + url.replace( /^\/+/, '' );
+	return buildFullPath( request.baseURL, request.url );
+}
+
+/**
+ * Given an Axios request config this function generates the URL that Axios will
+ * use to make the request with the query parameters included.
+ *
+ * @param {AxiosRequestConfig} request The Axios request we're building the URL for.
+ * @return {string} The merged URL.
+ */
+export function buildURLWithParams( request: AxiosRequestConfig ): string {
+	return appendParams( buildURL( request ), request.params, request.paramsSerializer );
 }