diff --git a/Core/MIPS/x86/X64IRAsm.cpp b/Core/MIPS/x86/X64IRAsm.cpp
index 7282bc68d4..cbbfff09dc 100644
--- a/Core/MIPS/x86/X64IRAsm.cpp
+++ b/Core/MIPS/x86/X64IRAsm.cpp
@@ -58,6 +58,7 @@ void X64JitBackend::GenerateFixedCode(MIPSState *mipsState) {
 		//regs_.EmitSaveStaticRegisters();
 		RET();
 
+		// Note: needs to not modify EAX, or to save it if it does.
 		loadStaticRegisters_ = AlignCode16();
 		//regs_.EmitLoadStaticRegisters();
 		//MOV(32, R(DOWNCOUNTREG), MDisp(CTXREG, downcountOffset));
diff --git a/Core/MIPS/x86/X64IRCompSystem.cpp b/Core/MIPS/x86/X64IRCompSystem.cpp
index 0c2f7ef66e..2d4f5db7f7 100644
--- a/Core/MIPS/x86/X64IRCompSystem.cpp
+++ b/Core/MIPS/x86/X64IRCompSystem.cpp
@@ -124,6 +124,14 @@ void X64JitBackend::CompIR_System(IRInst inst) {
 		break;
 
 	case IROp::CallReplacement:
+		FlushAll();
+		SaveStaticRegisters();
+		ABI_CallFunction(GetReplacementFunc(inst.constant)->replaceFunc);
+		LoadStaticRegisters();
+		//SUB(32, R(DOWNCOUNTREG), R(DOWNCOUNTREG), R(EAX));
+		SUB(32, MDisp(CTXREG, downcountOffset), R(EAX));
+		break;
+
 	case IROp::Break:
 		CompIR_Generic(inst);
 		break;