diff --git a/Common/ABI.cpp b/Common/ABI.cpp
index 7f42580946..d566dea8cc 100644
--- a/Common/ABI.cpp
+++ b/Common/ABI.cpp
@@ -514,7 +514,7 @@ void XEmitter::ABI_PushAllCalleeSavedRegsAndAdjustStack() {
 	PUSH(R15);
 	ABI_AlignStack(0);
 
-	// Do this after aligning, beacuse before it's offset by 8.
+	// Do this after aligning, because before it's offset by 8.
 	SUB(64, R(RSP), Imm32(XMM_STACK_SPACE));
 	for (int i = 0; i < 16; ++i)
 		MOVAPS(MDisp(RSP, i * 16), (X64Reg)(XMM0 + i));
diff --git a/Common/Thunk.cpp b/Common/Thunk.cpp
index 5356a2334f..1e66caf287 100644
--- a/Common/Thunk.cpp
+++ b/Common/Thunk.cpp
@@ -24,9 +24,11 @@
 namespace
 {
 
+#ifndef _M_X64
 static u8 GC_ALIGNED32(saved_fp_state[16 * 4 * 4]);
 static u8 GC_ALIGNED32(saved_gpr_state[16 * 8]);
 static u16 saved_mxcsr;
+#endif
 
 }  // namespace
 
@@ -34,45 +36,60 @@ using namespace Gen;
 
 void ThunkManager::Init()
 {
+#ifdef _M_X64
+	// Account for the return address.
+	int stackOffset = 0x8;
+	int stackPosition;
+#endif
+
 	AllocCodeSpace(THUNK_ARENA_SIZE);
 	save_regs = GetCodePtr();
+#ifdef _M_X64
+	for (int i = 2; i < ABI_GetNumXMMRegs(); i++)
+		MOVAPS(MDisp(RSP, stackOffset + (i - 2) * 16), (X64Reg)(XMM0 + i));
+	stackPosition = (ABI_GetNumXMMRegs() - 2) * 2;
+	STMXCSR(MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+	MOV(64, MDisp(RSP, stackOffset + (stackPosition++ * 8)), R(RCX));
+	MOV(64, MDisp(RSP, stackOffset + (stackPosition++ * 8)), R(RDX));
+	MOV(64, MDisp(RSP, stackOffset + (stackPosition++ * 8)), R(R8) );
+	MOV(64, MDisp(RSP, stackOffset + (stackPosition++ * 8)), R(R9) );
+	MOV(64, MDisp(RSP, stackOffset + (stackPosition++ * 8)), R(R10));
+	MOV(64, MDisp(RSP, stackOffset + (stackPosition++ * 8)), R(R11));
+#ifndef _WIN32
+	MOV(64, MDisp(RSP, stackOffset + (stackPosition++ * 8)), R(RSI));
+	MOV(64, MDisp(RSP, stackOffset + (stackPosition++ * 8)), R(RDI));
+#endif
+	MOV(64, MDisp(RSP, stackOffset + (stackPosition++ * 8)), R(RBX));
+#else
 	for (int i = 2; i < ABI_GetNumXMMRegs(); i++)
 		MOVAPS(M(saved_fp_state + i * 16), (X64Reg)(XMM0 + i));
 	STMXCSR(M(&saved_mxcsr));
-#ifdef _M_X64
-	MOV(64, M(saved_gpr_state + 0 ), R(RCX));
-	MOV(64, M(saved_gpr_state + 8 ), R(RDX));
-	MOV(64, M(saved_gpr_state + 16), R(R8) );
-	MOV(64, M(saved_gpr_state + 24), R(R9) );
-	MOV(64, M(saved_gpr_state + 32), R(R10));
-	MOV(64, M(saved_gpr_state + 40), R(R11));
-#ifndef _WIN32
-	MOV(64, M(saved_gpr_state + 48), R(RSI));
-	MOV(64, M(saved_gpr_state + 56), R(RDI));
-#endif
-	MOV(64, M(saved_gpr_state + 64), R(RBX));
-#else
 	MOV(32, M(saved_gpr_state + 0 ), R(RCX));
 	MOV(32, M(saved_gpr_state + 4 ), R(RDX));
 #endif
 	RET();
+
 	load_regs = GetCodePtr();
+#ifdef _M_X64
+	for (int i = 2; i < ABI_GetNumXMMRegs(); i++)
+		MOVAPS((X64Reg)(XMM0 + i), MDisp(RSP, stackOffset + (i - 2) * 16));
+	stackPosition = (ABI_GetNumXMMRegs() - 2) * 2;
+	LDMXCSR(MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+	MOV(64, R(RCX), MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+	MOV(64, R(RDX), MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+	MOV(64, R(R8) , MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+	MOV(64, R(R9) , MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+	MOV(64, R(R10), MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+	MOV(64, R(R11), MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+#ifndef _WIN32
+	MOV(64, R(RSI), MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+	MOV(64, R(RDI), MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+#endif
+	MOV(64, R(RBX), MDisp(RSP, stackOffset + (stackPosition++ * 8)));
+#else
 	LDMXCSR(M(&saved_mxcsr));
 	for (int i = 2; i < ABI_GetNumXMMRegs(); i++)
 		MOVAPS((X64Reg)(XMM0 + i), M(saved_fp_state + i * 16));
-#ifdef _M_X64
-	MOV(64, R(RCX), M(saved_gpr_state + 0 ));
-	MOV(64, R(RDX), M(saved_gpr_state + 8 ));
-	MOV(64, R(R8) , M(saved_gpr_state + 16));
-	MOV(64, R(R9) , M(saved_gpr_state + 24));
-	MOV(64, R(R10), M(saved_gpr_state + 32));
-	MOV(64, R(R11), M(saved_gpr_state + 40));
-#ifndef _WIN32
-	MOV(64, R(RSI), M(saved_gpr_state + 48));
-	MOV(64, R(RDI), M(saved_gpr_state + 56));
-#endif
-	MOV(64, R(RBX), M(saved_gpr_state + 64));
-#else
 	MOV(32, R(RCX), M(saved_gpr_state + 0 ));
 	MOV(32, R(RDX), M(saved_gpr_state + 4 ));
 #endif
@@ -91,6 +108,39 @@ void ThunkManager::Shutdown()
 	FreeCodeSpace();
 }
 
+int ThunkManager::ThunkBytesNeeded()
+{
+	int space = (ABI_GetNumXMMRegs() - 2) * 16;
+#ifdef _M_X64
+	// MXCSR
+	space += 8;
+	space += 7 * 8;
+#ifndef _WIN32
+	space += 2 * 8;
+#endif
+#else
+	// MXCSR
+	space += 4;
+	space += 2 * 4;
+#endif
+
+	// Round up to the nearest 16 just in case.
+	return (space + 15) & ~15;
+}
+
+int ThunkManager::ThunkStackOffset()
+{
+#ifdef _M_X64
+#ifdef _WIN32
+	return 0x28;
+#else
+	return 0x8;
+#endif
+#else
+	return 0;
+#endif
+}
+
 const void *ThunkManager::ProtectFunction(const void *function, int num_params)
 {
 	std::map<const void *, const u8 *>::iterator iter;
@@ -103,19 +153,11 @@ const void *ThunkManager::ProtectFunction(const void *function, int num_params)
 	const u8 *call_point = GetCodePtr();
 	// Make sure to align stack.
 #ifdef _M_X64
-#ifdef _WIN32
-	SUB(64, R(ESP), Imm8(0x28));
-#else
-	SUB(64, R(ESP), Imm8(0x8));
-#endif
+	SUB(64, R(ESP), Imm32(ThunkStackOffset() + ThunkBytesNeeded()));
 	ABI_CallFunction(save_regs);
 	ABI_CallFunction(function);
 	ABI_CallFunction(load_regs);
-#ifdef _WIN32
-	ADD(64, R(ESP), Imm8(0x28));
-#else
-	ADD(64, R(ESP), Imm8(0x8));
-#endif
+	ADD(64, R(ESP), Imm32(ThunkStackOffset() + ThunkBytesNeeded()));
 	RET();
 #else
 	CALL((const void *)save_regs);
diff --git a/Common/Thunk.h b/Common/Thunk.h
index 16d14db942..b6513a2d10 100644
--- a/Common/Thunk.h
+++ b/Common/Thunk.h
@@ -94,6 +94,9 @@ private:
 	void Init();
 	void Shutdown();
 	void Reset();
+
+	int ThunkStackOffset();
+	int ThunkBytesNeeded();
 };
 
 #endif // _THUNK_H_