diff --git a/source/base/StarAssets.cpp b/source/base/StarAssets.cpp
index b334b31..357fca0 100644
--- a/source/base/StarAssets.cpp
+++ b/source/base/StarAssets.cpp
@@ -147,8 +147,10 @@ Assets::Assets(Settings settings, StringList assetSources) {
   pushGlobalContext("assets", makeBaseAssetCallbacks());
 
   auto decorateLuaContext = [&](LuaContext& context, MemoryAssetSourcePtr newFiles) {
-    auto callbacks = makeBaseAssetCallbacks();
     if (newFiles) {
+      // re-add the assets callbacks with more functions
+      context.remove("assets");
+      auto callbacks = makeBaseAssetCallbacks();
       callbacks.registerCallback("add", [&newFiles](LuaEngine& engine, String const& path, LuaValue const& data) {
         ByteArray bytes;
         if (auto str = engine.luaMaybeTo<String>(data))
@@ -184,9 +186,9 @@ Assets::Assets(Settings settings, StringList assetSources) {
           m_filesByExtension[AssetPath::extension(path).toLower()].erase(path);
         return erased;
       });
-    }
 
-    context.setCallbacks("assets", callbacks);
+      context.setCallbacks("assets", callbacks);
+    }
   };
 
   auto addSource = [&](String const& sourcePath, AssetSourcePtr source) {
diff --git a/source/base/StarMixer.cpp b/source/base/StarMixer.cpp
index 2e52afc..72a6cd6 100644
--- a/source/base/StarMixer.cpp
+++ b/source/base/StarMixer.cpp
@@ -231,6 +231,7 @@ void Mixer::stopAll(float rampTime) {
 void Mixer::read(int16_t* outBuffer, size_t frameCount, ExtraMixFunction extraMixFunction) {
   // Make this method as least locky as possible by copying all the needed
   // member data before the expensive audio / effect stuff.
+  float speed;
   unsigned sampleRate;
   unsigned channels;
   float volume;
@@ -240,6 +241,7 @@ void Mixer::read(int16_t* outBuffer, size_t frameCount, ExtraMixFunction extraMi
 
   {
     MutexLocker locker(m_mutex);
+    speed = m_speed;
     sampleRate = m_sampleRate;
     channels = m_channels;
     volume = m_volume.value;
@@ -266,8 +268,6 @@ void Mixer::read(int16_t* outBuffer, size_t frameCount, ExtraMixFunction extraMi
   for (size_t i = 0; i < bufferSize; ++i)
     outBuffer[i] = 0;
 
-  float speed = m_speed;
-
   {
     MutexLocker locker(m_queueMutex);
     // Mix all active sounds