diff --git a/Core/CoreParameter.h b/Core/CoreParameter.h
index 22b75f18e8..9558ba2cac 100644
--- a/Core/CoreParameter.h
+++ b/Core/CoreParameter.h
@@ -55,6 +55,10 @@ struct CoreParameter {
 	CPUCore cpuCore;
 	GPUCore gpuCore;
 
+	// Independent of cpuCore. Standalone turns it on wherever the host can JIT; headless keeps it
+	// off, since the test references were recorded with the C++ vertex decoder.
+	bool bUseVertexDecoderJit = false;
+
 	GraphicsContext *graphicsContext = nullptr;  // TODO: Find a better place.
 	bool enableSound = true;  // there aren't multiple sound cores.
 
diff --git a/GPU/Common/DrawEngineCommon.cpp b/GPU/Common/DrawEngineCommon.cpp
index 8c0a6d3bcc..09bf16b891 100644
--- a/GPU/Common/DrawEngineCommon.cpp
+++ b/GPU/Common/DrawEngineCommon.cpp
@@ -44,7 +44,7 @@ enum {
 };
 
 DrawEngineCommon::DrawEngineCommon() : decoderMap_(32) {
-	if (g_Config.bVertexDecoderJit && (g_Config.iCpuCore == (int)CPUCore::JIT || g_Config.iCpuCore == (int)CPUCore::JIT_IR)) {
+	if (g_Config.bVertexDecoderJit && PSP_CoreParameter().bUseVertexDecoderJit) {
 		decJitCache_ = new VertexDecoderJitCache();
 	}
 	transformed_ = (TransformedVertex *)AllocateMemoryPages(TRANSFORMED_VERTEX_BUFFER_SIZE, MEM_PROT_READ | MEM_PROT_WRITE);
diff --git a/GPU/Common/VertexDecoderCommon.cpp b/GPU/Common/VertexDecoderCommon.cpp
index 7fd37575b0..a9e6cad933 100644
--- a/GPU/Common/VertexDecoderCommon.cpp
+++ b/GPU/Common/VertexDecoderCommon.cpp
@@ -27,7 +27,6 @@
 #include "Common/Math/CrossSIMD.h"
 #include "Common/Log.h"
 #include "Common/LogReporting.h"
-#include "Core/Config.h"
 #include "Core/ConfigValues.h"
 #include "Core/HDRemaster.h"
 #include "Core/MIPS/JitCommon/JitCommon.h"
@@ -1623,10 +1622,7 @@ VertexDecoderJitCache::VertexDecoderJitCache()
 }
 
 void VertexDecoderJitCache::Clear() {
-	// TODO: These should check CoreParameter instead.
-	if (g_Config.iCpuCore == (int)CPUCore::JIT || g_Config.iCpuCore == (int)CPUCore::JIT_IR) {
-		ClearCodeSpace(0);
-	}
+	ClearCodeSpace(0);
 }
 
 struct StepFunctionNameEntry {
diff --git a/UI/EmuScreen.cpp b/UI/EmuScreen.cpp
index 014db251d9..677ef5d4d0 100644
--- a/UI/EmuScreen.cpp
+++ b/UI/EmuScreen.cpp
@@ -282,6 +282,7 @@ void EmuScreen::ProcessGameBoot(const Path &filename) {
 
 	CoreParameter coreParam{};
 	coreParam.cpuCore = (CPUCore)g_Config.iCpuCore;
+	coreParam.bUseVertexDecoderJit = System_GetPropertyBool(SYSPROP_CAN_JIT);
 	coreParam.gpuCore = GPUCORE_GLES;
 	switch (GetGPUBackend()) {
 	case GPUBackend::DIRECT3D11:
diff --git a/headless/Headless.cpp b/headless/Headless.cpp
index cfc73f1095..414bd04cc3 100644
--- a/headless/Headless.cpp
+++ b/headless/Headless.cpp
@@ -835,8 +835,7 @@ int main(int argc, const char* argv[]) {
 
 	// Force known values for deterministic test execution. This happens before
 	// ApplyToConfig() below, so a matching command line flag can still override any of it -
-	// ApplyToConfig() always has the final say on the settings in g_Config - except for iCpuCore,
-	// which is forced after it instead, see below.
+	// ApplyToConfig() always has the final say on the settings in g_Config.
 
 	// NOTE: In headless mode, we never save the config. This is just for this run.
 	g_Config.iDumpFileTypes = 0;
@@ -889,14 +888,6 @@ int main(int argc, const char* argv[]) {
 	// overrides above, so a matching command line flag always wins.
 	cmdLineOptions.ApplyToConfig();
 
-	// The exception to that, forced after ApplyToConfig() so --cpu can't reach it. g_Config.iCpuCore
-	// doesn't pick the MIPS core here (CoreParameter below does, straight from the command line) -
-	// it also gates the vertex decoder JIT, in the DrawEngineCommon constructor. Letting --cpu=jit
-	// switch that on decodes vertices through a different path and changes the output of a dozen or
-	// so GPU tests, gpu/vertices/morph among them. The core to test is a CPU question, so keep the
-	// GPU side on one path for every backend.
-	g_Config.iCpuCore = (int)CPUCore::INTERPRETER;
-
 	// pspautotests is plain homebrew PRXes so do not ship user libraries that a retail disc may carry. 
 	// So we must use HLE, unless we install firmware.
 	// A disc brings its own copies and the app runs them for real, so
@@ -907,8 +898,6 @@ int main(int argc, const char* argv[]) {
 		g_Config.iForceEnableHLE = 0xFFFFFFFF & ~g_Config.iDisableHLE;
 	}
 
-	// This looks contradictory to above checks. But, this preserves the old test behavior which apparently ran the JIT for the CPU
-	// but ended up running software vertex decoding due to the setting in g_Config. Yeah, it's a mess.
 	CPUCore cpuCore = CPUCore::JIT;
 	if (cmdLineOptions.cpuCore.has_value()) {
 		cpuCore = cmdLineOptions.cpuCore.value();
@@ -963,6 +952,9 @@ int main(int argc, const char* argv[]) {
 	// but not now.
 	CoreParameter coreParameter;
 	coreParameter.cpuCore = (CPUCore)cpuCore;
+	// The pspautotests expectations and frametest references were recorded with the C++ vertex
+	// decoder, and the JIT decoders don't match it everywhere yet.
+	coreParameter.bUseVertexDecoderJit = false;
 	coreParameter.gpuCore = (GPUCore)gpuCore;
 	coreParameter.graphicsContext = graphicsContext;
 	coreParameter.enableSound = false;
diff --git a/libretro/libretro.cpp b/libretro/libretro.cpp
index 8f2830bdbb..a217af86f6 100644
--- a/libretro/libretro.cpp
+++ b/libretro/libretro.cpp
@@ -1512,6 +1512,7 @@ bool retro_load_game(const struct retro_game_info *game) {
 
    // set cpuCore from libretro setting variable
    coreParam.cpuCore         =  (CPUCore)g_Config.iCpuCore;
+   coreParam.bUseVertexDecoderJit = System_GetPropertyBool(SYSPROP_CAN_JIT);
 
    g_pendingBoot = true;