diff --git a/Core/HLE/sceAudiocodec.cpp b/Core/HLE/sceAudiocodec.cpp
index 29b0449b34..cb00a38b5a 100644
--- a/Core/HLE/sceAudiocodec.cpp
+++ b/Core/HLE/sceAudiocodec.cpp
@@ -210,6 +210,9 @@ static void clearDecoders() {
 }
 
 void __AudioCodecInit() {
+	// findDecoder keys on a game-chosen context address, so don't leave decoders from a previous
+	// game around for the next one to find.
+	clearDecoders();
 	oldStateLoaded = false;
 }
 
diff --git a/Core/HLE/sceMpeg.cpp b/Core/HLE/sceMpeg.cpp
index 99c295a757..70e4c065a0 100644
--- a/Core/HLE/sceMpeg.cpp
+++ b/Core/HLE/sceMpeg.cpp
@@ -348,8 +348,18 @@ private:
 	s32 remainingPackets_ = 0;
 };
 
+static void ClearMpegContexts() {
+	for (const auto &[_, ctx] : g_mpegCtxs) {
+		delete ctx;
+	}
+	g_mpegCtxs.clear();
+}
+
 void __MpegInit() {
 	__MpegBaseInit();
+	// getMpegCtx keys on a handle read out of game memory, so don't leave contexts from a previous
+	// game around for the next one to find.
+	ClearMpegContexts();
 	isMpegInit = false;
 	mpegLibVersion = 0x010A;
 	streamIdGen = 1;
@@ -403,11 +413,7 @@ void __MpegDoState(PointerWrap &p) {
 }
 
 void __MpegShutdown() {
-	std::map<u32, MpegContext *>::iterator it, end;
-	for (it = g_mpegCtxs.begin(), end = g_mpegCtxs.end(); it != end; ++it) {
-		delete it->second;
-	}
-	g_mpegCtxs.clear();
+	ClearMpegContexts();
 }
 
 void __MpegLoadModule(int version,u32 crc) {
diff --git a/Core/HLE/sceVideocodec.cpp b/Core/HLE/sceVideocodec.cpp
index b9489ce120..6e74aefeec 100644
--- a/Core/HLE/sceVideocodec.cpp
+++ b/Core/HLE/sceVideocodec.cpp
@@ -162,8 +162,9 @@ static void ClearContexts(bool freeMemory) {
 }
 
 void __VideocodecInit() {
-	// Nothing to free: a boot starts with a fresh allocator.
-	g_videocodecCtxs.clear();
+	// The decoders have to be deleted; the ME blocks they hold don't need freeing individually,
+	// since the allocator is emptied right below.
+	ClearContexts(false);
 	g_meRam.clear();
 	g_meRam.shrink_to_fit();
 	g_meAlloc.Shutdown();
diff --git a/headless/Headless.cpp b/headless/Headless.cpp
index 4450558d1d..1f58b1f87e 100644
--- a/headless/Headless.cpp
+++ b/headless/Headless.cpp
@@ -785,6 +785,10 @@ int main(int argc, const char* argv[]) {
 	g_Config.iInternalResolution = cmdLineOptions.resolutionScale.value_or(1);
 	g_Config.bEnableLogging = (fullLog || outputDebugStringLog);
 	g_Config.bVertexDecoderJit = true;
+	// Headless never loads a config file, so anything not set here keeps the zero-initialized
+	// value rather than the ConfigSetting default. This one defaults to true in the app, and
+	// leaving it false made headless run games differently from every other build.
+	g_Config.bFuncReplacements = true;
 	g_Config.bSoftwareRendering = cmdLineOptions.softwareRendering.value_or(false);
 	g_Config.bSoftwareRenderingJit = true;
 	g_Config.iSplineBezierQuality = 2;