diff --git a/CHANGELOG.md b/CHANGELOG.md
index af22c13..9ce23d7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 - Removed support for Node.js below 12
 - Added support for asynchronous creators (#54)
 - Added optional `direction` parameter to middlewares (#53)
+- Added a deep merge of injector settings (#52)
 - Updated dependencies
 
 ## 0.14.3
diff --git a/src/server/core/config.ts b/src/server/core/config.ts
index f0511cd..708137f 100644
--- a/src/server/core/config.ts
+++ b/src/server/core/config.ts
@@ -89,6 +89,25 @@ export function readConfiguration(path: string): ConfigurationFile {
   return {};
 }
 
+function deepMerge(obj: any, value: any) {
+  Object.keys(value).forEach((key) => {
+    const oldItem = obj[key];
+    const newItem = value[key];
+
+    if (newItem === undefined) {
+      delete obj[key];
+    } else if (Array.isArray(oldItem) && Array.isArray(newItem)) {
+      obj[key] = [...oldItem, ...newItem] as any;
+    } else if (typeof oldItem === 'object') {
+      obj[key] = deepMerge({ ...oldItem }, newItem);
+    } else {
+      obj[key] = newItem;
+    }
+  });
+
+  return obj;
+}
+
 function mergeObjects<T>(
   sources: Array<Partial<KrasConfiguration>>,
   select: (config: Partial<KrasConfiguration>) => Dict<T>,
@@ -99,21 +118,7 @@ function mergeObjects<T>(
     const value = select(source);
 
     if (value && typeof value === 'object') {
-      Object.keys(value).forEach((key) => {
-        const oldItem = obj[key];
-        const newItem = value[key];
-
-        if (newItem === undefined) {
-          delete obj[key];
-        } else if (typeof oldItem === 'object') {
-          obj[key] = {
-            ...oldItem,
-            ...newItem,
-          };
-        } else {
-          obj[key] = newItem;
-        }
-      });
+      deepMerge(obj, value);
     }
   }
 
diff --git a/src/server/core/webserver.ts b/src/server/core/webserver.ts
index 547758d..f23ab8f 100644
--- a/src/server/core/webserver.ts
+++ b/src/server/core/webserver.ts
@@ -222,7 +222,11 @@ export class WebServer extends EventEmitter implements BaseKrasServer {
     return api;
   }
 
-  start() {
+  async setup() {}
+
+  async start() {
+    await this.setup();
+
     this.app.all('*', (req: Request, res: Response) => {
       if (req.method !== 'OPTIONS') {
         const hook = findHook(this.hooks, req);
@@ -239,7 +243,7 @@ export class WebServer extends EventEmitter implements BaseKrasServer {
       return corsHandler(req, res);
     });
 
-    return new Promise<void>((resolve) => {
+    return await new Promise<void>((resolve) => {
       this.server.listen(this.port, () => {
         this.emit('open', {
           port: this.port,
diff --git a/src/server/server.ts b/src/server/server.ts
index e532ede..3cf8b3a 100644
--- a/src/server/server.ts
+++ b/src/server/server.ts
@@ -55,7 +55,7 @@ export class MockServer extends MockServerCore implements KrasServer {
   readonly logs: Array<LogEntry> = [];
   readonly logLevel: LogLevel;
 
-  constructor(config: KrasConfiguration) {
+  constructor(private config: KrasConfiguration) {
     super(config);
 
     this.logLevel = config.logLevel || 'error';
@@ -66,15 +66,18 @@ export class MockServer extends MockServerCore implements KrasServer {
     }
   }
 
-  async setup(config: KrasConfiguration) {
+  async setup() {
+    const config = this.config;
+    await super.setup();
     await withManagement(this, config);
     await withInjectors(this, config);
     await withMiddlewares(this, config);
     await withFiles(this, config);
   }
 
-  stop() {
-    return super.stop().then(() => this.injectors.forEach(disposeInjector));
+  async stop() {
+    await super.stop();
+    this.injectors.forEach(disposeInjector);
   }
 
   private log(type: LogEntryType, data: any) {
@@ -98,30 +101,28 @@ export function readKrasConfig(options?: ConfigurationOptions, ...files: Array<s
   return mergeConfiguration(options, ...configurations);
 }
 
-export async function buildKras(config?: Partial<KrasConfiguration>) {
+export function buildKras(config?: Partial<KrasConfiguration>) {
   const options = buildConfiguration(config);
-  const server = new MockServer(options);
-  await server.setup(options);
-  return server;
+  return new MockServer(options);
 }
 
-export async function buildKrasWithCli(config: KrasConfiguration) {
-  const server = await buildKras(config);
+export function buildKrasWithCli(config: KrasConfiguration) {
+  const server = buildKras(config);
   connectToCli(server, config.api !== false);
   return server;
 }
 
 export async function runKras(config?: Partial<KrasConfiguration>) {
-  const server = await buildKras(config);
-  server.start();
+  const server = buildKras(config);
+  await server.start();
   return server;
 }
 
 export type KrasRuntimeConfiguration = Partial<KrasConfiguration> & KrasHandlerConfiguration;
 
 export function withKras(config?: KrasRuntimeConfiguration) {
-  return async (callback: KrasRunner) => {
-    const server = await buildKras(config);
+  return (callback: KrasRunner) => {
+    const server = buildKras(config);
     configureHandler(server, config);
     return runWith(server, callback);
   };
@@ -205,8 +206,8 @@ export function connectToCli(server: MockServer, canManage = true) {
 
 export async function runFromCli(options: ConfigurationOptions, rcfile: string) {
   const config = readKrasConfig(options, resolve(homedir(), krasrc), resolve(currentDir, krasrc), rcfile);
-  const server = await buildKrasWithCli(config);
+  const server = buildKrasWithCli(config);
   console.log(`Starting kras v${version} ...`);
-  server.start();
+  await server.start();
   return server;
 }