diff --git a/packages/platform-server/src/http.ts b/packages/platform-server/src/http.ts
index 682da84fa0..d165be953b 100644
--- a/packages/platform-server/src/http.ts
+++ b/packages/platform-server/src/http.ts
@@ -10,13 +10,12 @@
 const xhr2: any = require('xhr2');
 
 import {Injectable, Injector, Provider} from '@angular/core';
-import {DOCUMENT} from '@angular/common';
+import {PlatformLocation} from '@angular/common';
 import {HttpEvent, HttpRequest, HttpHandler, HttpBackend, XhrFactory, ɵHttpInterceptingHandler as HttpInterceptingHandler} from '@angular/common/http';
 import {Observable, Observer, Subscription} from 'rxjs';
 
 // @see https://www.w3.org/Protocols/HTTP/1.1/draft-ietf-http-v11-spec-01#URI-syntax
 const isAbsoluteUrl = /^[a-zA-Z\-\+.]+:\/\//;
-const FORWARD_SLASH = '/';
 
 @Injectable()
 export class ServerXhr implements XhrFactory {
@@ -105,20 +104,18 @@ export abstract class ZoneMacroTaskWrapper<S, R> {
 
 export class ZoneClientBackend extends
     ZoneMacroTaskWrapper<HttpRequest<any>, HttpEvent<any>> implements HttpBackend {
-  constructor(private backend: HttpBackend, private doc: Document) {
+  constructor(private backend: HttpBackend, private platformLocation: PlatformLocation) {
     super();
   }
 
   handle(request: HttpRequest<any>): Observable<HttpEvent<any>> {
-    const href = this.doc.location.href;
-    if (!isAbsoluteUrl.test(request.url) && href) {
-      const urlParts = Array.from(request.url);
-      if (request.url[0] === FORWARD_SLASH && href[href.length - 1] === FORWARD_SLASH) {
-        urlParts.shift();
-      } else if (request.url[0] !== FORWARD_SLASH && href[href.length - 1] !== FORWARD_SLASH) {
-        urlParts.splice(0, 0, FORWARD_SLASH);
-      }
-      return this.wrap(request.clone({url: href + urlParts.join('')}));
+    const {href, protocol, hostname} = this.platformLocation;
+    if (!isAbsoluteUrl.test(request.url) && href !== '/') {
+      const baseHref = this.platformLocation.getBaseHrefFromDOM() || href;
+      const urlPrefix = `${protocol}//${hostname}`;
+      const baseUrl = new URL(baseHref, urlPrefix);
+      const url = new URL(request.url, baseUrl);
+      return this.wrap(request.clone({url: url.toString()}));
     }
     return this.wrap(request);
   }
@@ -129,15 +126,15 @@ export class ZoneClientBackend extends
 }
 
 export function zoneWrappedInterceptingHandler(
-    backend: HttpBackend, injector: Injector, doc: Document) {
+    backend: HttpBackend, injector: Injector, platformLocation: PlatformLocation) {
   const realBackend: HttpBackend = new HttpInterceptingHandler(backend, injector);
-  return new ZoneClientBackend(realBackend, doc);
+  return new ZoneClientBackend(realBackend, platformLocation);
 }
 
 export const SERVER_HTTP_PROVIDERS: Provider[] = [
   {provide: XhrFactory, useClass: ServerXhr}, {
     provide: HttpHandler,
     useFactory: zoneWrappedInterceptingHandler,
-    deps: [HttpBackend, Injector, DOCUMENT]
+    deps: [HttpBackend, Injector, PlatformLocation]
   }
 ];
diff --git a/packages/platform-server/src/location.ts b/packages/platform-server/src/location.ts
index 18c3c8da87..60f42c793b 100644
--- a/packages/platform-server/src/location.ts
+++ b/packages/platform-server/src/location.ts
@@ -51,6 +51,7 @@ export class ServerPlatformLocation implements PlatformLocation {
       this.pathname = parsedUrl.pathname;
       this.search = parsedUrl.search;
       this.hash = parsedUrl.hash;
+      this.href = _doc.location.href;
     }
   }
 
diff --git a/packages/platform-server/test/integration_spec.ts b/packages/platform-server/test/integration_spec.ts
index d0fbfa0f3c..db3d334e55 100644
--- a/packages/platform-server/test/integration_spec.ts
+++ b/packages/platform-server/test/integration_spec.ts
@@ -841,6 +841,58 @@ describe('platform-server integration', () => {
       });
     });
 
+    it('can make relative HttpClient requests no slashes longer url', async () => {
+      const platform = platformDynamicServer([{
+        provide: INITIAL_CONFIG,
+        useValue: {document: '<app></app>', url: 'http://localhost/path/page'}
+      }]);
+      const ref = await platform.bootstrapModule(HttpClientExampleModule);
+      const mock = ref.injector.get(HttpTestingController) as HttpTestingController;
+      const http = ref.injector.get(HttpClient);
+      ref.injector.get(NgZone).run(() => {
+        http.get<string>('testing').subscribe((body: string) => {
+          NgZone.assertInAngularZone();
+          expect(body).toEqual('success!');
+        });
+        mock.expectOne('http://localhost/path/testing').flush('success!');
+      });
+    });
+
+    it('can make relative HttpClient requests slashes longer url', async () => {
+      const platform = platformDynamicServer([{
+        provide: INITIAL_CONFIG,
+        useValue: {document: '<app></app>', url: 'http://localhost/path/page'}
+      }]);
+      const ref = await platform.bootstrapModule(HttpClientExampleModule);
+      const mock = ref.injector.get(HttpTestingController) as HttpTestingController;
+      const http = ref.injector.get(HttpClient);
+      ref.injector.get(NgZone).run(() => {
+        http.get<string>('/testing').subscribe((body: string) => {
+          NgZone.assertInAngularZone();
+          expect(body).toEqual('success!');
+        });
+        mock.expectOne('http://localhost/testing').flush('success!');
+      });
+    });
+
+    it('can make relative HttpClient requests slashes longer url with base href', async () => {
+      const platform = platformDynamicServer([{
+        provide: INITIAL_CONFIG,
+        useValue:
+            {document: '<base href="http://other"><app></app>', url: 'http://localhost/path/page'}
+      }]);
+      const ref = await platform.bootstrapModule(HttpClientExampleModule);
+      const mock = ref.injector.get(HttpTestingController) as HttpTestingController;
+      const http = ref.injector.get(HttpClient);
+      ref.injector.get(NgZone).run(() => {
+        http.get<string>('/testing').subscribe((body: string) => {
+          NgZone.assertInAngularZone();
+          expect(body).toEqual('success!');
+        });
+        mock.expectOne('http://other/testing').flush('success!');
+      });
+    });
+
     it('requests are macrotasks', async(() => {
          const platform = platformDynamicServer(
              [{provide: INITIAL_CONFIG, useValue: {document: '<app></app>'}}]);