diff --git a/Makefile b/Makefile
index d879478ed..3fa9bf047 100644
--- a/Makefile
+++ b/Makefile
@@ -31,7 +31,8 @@ LDFLAGS=\
 	-s USE_FREETYPE=1 \
 	-std=c++14 \
   -lstdc++ \
-  --memory-init-file 0
+  --memory-init-file 0 \
+  --minify 0
 
 SIX_ROOT=six/six-1.11.0/build/lib
 SIX_LIBS=$(SIX_ROOT)/six.py
@@ -62,7 +63,7 @@ build/pyodide.asm.js: src/main.bc src/jsimport.bc src/jsproxy.bc src/js2python.b
 
 
 build/pyodide.asm.data: root/.built
-	python2 $(FILEPACKAGER) build/pyodide.asm.data --preload root/lib@lib --js-output=build/pyodide.asm.data.js
+	python2 $(FILEPACKAGER) build/pyodide.asm.data --preload root/lib@lib --js-output=build/pyodide.asm.data.js --use-preload-plugins
 	uglifyjs build/pyodide.asm.data.js -o build/pyodide.asm.data.js
 
 
diff --git a/src/pyodide.js b/src/pyodide.js
index 52fc51fe0..f8aaf0dfc 100644
--- a/src/pyodide.js
+++ b/src/pyodide.js
@@ -71,22 +71,40 @@ var languagePluginLoader = new Promise((resolve, reject) => {
   let Module = {};
   window.Module = Module;
 
+  Module.noImageDecoding = true;
+  Module.noAudioDecoding = true;
+
   let wasm_promise = WebAssembly.compileStreaming(fetch(wasmURL));
   Module.instantiateWasm = (info, receiveInstance) => {
-    wasm_promise.then(module => WebAssembly.instantiate(module, info))
-        .then(instance => receiveInstance(instance));
+    wasm_promise
+      .then(module => WebAssembly.instantiate(module, info))
+      .then(instance => receiveInstance(instance));
     return {};
   };
+
   Module.filePackagePrefixURL = baseURL;
-  Module.postRun = () => {
-    delete window.Module;
-    fetch(`${baseURL}packages.json`)
+  var postRunPromise = new Promise((resolve, reject) => {
+    Module.postRun = () => {
+      delete window.Module;
+      fetch(`${baseURL}packages.json`)
         .then((response) => response.json())
         .then((json) => {
           window.pyodide.packages = json;
           resolve();
         });
-  };
+    };
+  });
+
+  var dataLoadPromise = new Promise((resolve, reject) => {
+    Module.monitorRunDependencies = (n) => {
+      if (n === 0) {
+        delete Module.monitorRunDependencies;
+        resolve();
+      }
+    }
+  });
+
+  Promise.all([postRunPromise, dataLoadPromise]).then(() => resolve());
 
   let data_script = document.createElement('script');
   data_script.src = `${baseURL}pyodide.asm.data.js`;