diff --git a/DulcificumJS/package-lock.json b/DulcificumJS/package-lock.json
index aee7c6d..0fe3735 100644
--- a/DulcificumJS/package-lock.json
+++ b/DulcificumJS/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@ultimaker/dulcificumjs",
-  "version": "0.1.0-alpha.5",
+  "version": "0.1.0-alpha.6",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@ultimaker/dulcificumjs",
-      "version": "0.1.0-alpha.5",
+      "version": "0.1.0-alpha.6",
       "dependencies": {
         "emscripten": "^0.0.2-beta"
       },
diff --git a/DulcificumJS/package.json b/DulcificumJS/package.json
index 90ecb17..b1e0ca2 100644
--- a/DulcificumJS/package.json
+++ b/DulcificumJS/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@ultimaker/dulcificumjs",
-  "version": "0.1.0-alpha.5",
+  "version": "0.1.0-alpha.6",
   "description": "DulcificumJS is a TS component to run Dulcificum in a browser",
   "main": "dist/index.js",
   "scripts": {
diff --git a/DulcificumJS/src/index.ts b/DulcificumJS/src/index.ts
index 57819f8..5197bd4 100644
--- a/DulcificumJS/src/index.ts
+++ b/DulcificumJS/src/index.ts
@@ -1,6 +1,6 @@
 import dulcificum, { MainModule } from './Dulcificum/dulcificum_js';
 
-let mod: MainModule = null;
+let mod: MainModule | null = null;
 
 /**
  * This must be executed and waited on before this module can be used.