diff --git a/package.json b/package.json
index 872f07c5abd44dd4678f32ca542306892942862a..7f854880567cdd56bb14b73c7122f08028d5718c 100644
--- a/package.json
+++ b/package.json
@@ -13,7 +13,7 @@
   "scripts": {
     "lint": "tslint src/**/*.ts",
     "test": "npm run lint && jest",
-    "build": "cpx \"src/**/*.{scss,woff,woff2,ttf,otf,eot,svg,html,gql}\" lib/ && tsc -b",
+    "build": "cpx \"src/**/*.{scss,woff,woff2,ttf,otf,eot,svg,html,gql}\" lib/ && tsc",
     "postinstall": "npm run build",
     "watch": "concurrently --kill-others \"npm:watch-ts\" \"npm:watch-extra\" \"npm:watch-webpack\"",
     "watch-ts": "tsc -watch",
diff --git a/src/servers/common/swagger-ui/index.ts b/src/servers/common/swagger-ui/index.ts
index 504cced90a290bee8e9c33f7691a27016289ebeb..fe93b0a0483adc081850a61db5111ee6a512da0e 100644
--- a/src/servers/common/swagger-ui/index.ts
+++ b/src/servers/common/swagger-ui/index.ts
@@ -9,8 +9,9 @@ import * as fs from 'fs'
 import { getAbsoluteFSPath } from 'swagger-ui-dist'
 import { ServeStaticOptions } from 'serve-static';
 import { interpolate } from '../../../mol-util/string';
+import { Handler } from 'express-serve-static-core';
 
-export function swaggerUiAssetsHandler(options?: ServeStaticOptions) {
+export function swaggerUiAssetsHandler(options?: ServeStaticOptions): Handler {
     const opts = options || {}
     opts.index = false
     return express.static(getAbsoluteFSPath(), opts)
diff --git a/src/servers/model/config.ts b/src/servers/model/config.ts
index a441e5085c03cb44da7aba53a31c2ee9e1a043ea..ac963eadf6789115e96101880ee7e61449d655bd 100644
--- a/src/servers/model/config.ts
+++ b/src/servers/model/config.ts
@@ -4,6 +4,8 @@
  * @author David Sehnal <david.sehnal@gmail.com>
  */
 
+import { ModelPropertyProviderConfig } from './property-provider';
+
 const config = {
     /**
      * Determine if and how long to cache entries after a request.
@@ -50,7 +52,7 @@ const config = {
     /**
      * Provide a property config or a path a JSON file with the config.
      */
-    customProperties: <import('./property-provider').ModelPropertyProviderConfig | string>{
+    customProperties: <ModelPropertyProviderConfig | string>{
         sources: [
             './properties/pdbe',
             './properties/rcsb'
diff --git a/src/servers/model/server/structure-wrapper.ts b/src/servers/model/server/structure-wrapper.ts
index ee6d556255cd07f276f7c018633cb85272ce5fc3..596ccd3e31bf4da7c763dff4c2df058d6b4a4f5b 100644
--- a/src/servers/model/server/structure-wrapper.ts
+++ b/src/servers/model/server/structure-wrapper.ts
@@ -8,7 +8,7 @@ import { Structure, Model } from '../../../mol-model/structure';
 import { PerformanceMonitor } from '../../../mol-util/performance-monitor';
 import { Cache } from './cache';
 import Config from '../config';
-import { CIF, CifFrame } from '../../../mol-io/reader/cif'
+import { CIF, CifFrame, CifBlock } from '../../../mol-io/reader/cif'
 import * as util from 'util'
 import * as fs from 'fs'
 import * as zlib from 'zlib'
@@ -90,7 +90,7 @@ async function parseCif(data: string|Uint8Array) {
     return parsed.result;
 }
 
-export async function readDataAndFrame(filename: string, key?: string) {
+export async function readDataAndFrame(filename: string, key?: string): Promise<{ data: string | Uint8Array, frame: CifBlock }> {
     perf.start('read');
     let data;
     try {
diff --git a/tsconfig.json b/tsconfig.json
index 96f6a540ec7332a6f022c397727e156b01c27064..c9ee2f8d7ee29dcf55dd02c679610cc340c7cf35 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,6 +1,5 @@
 {
     "compilerOptions": {
-        "composite": true,
         "declaration": true,
         "target": "es5",
         "alwaysStrict": true,