diff --git a/Core/MIPS/x86/CompVFPU.cpp b/Core/MIPS/x86/CompVFPU.cpp
index ad53308406..5ef039b99f 100644
--- a/Core/MIPS/x86/CompVFPU.cpp
+++ b/Core/MIPS/x86/CompVFPU.cpp
@@ -62,19 +62,17 @@ void Jit::Comp_VPFX(u32 op)
 	switch (regnum) {
 	case 0:  // S
 		js.prefixS = data;
-		js.prefixSKnown = true;
+		js.prefixSFlag = JitState::PREFIX_KNOWN_DIRTY;
 		break;
 	case 1:  // T
 		js.prefixT = data;
-		js.prefixTKnown = true;
+		js.prefixTFlag = JitState::PREFIX_KNOWN_DIRTY;
 		break;
 	case 2:  // D
 		js.prefixD = data;
-		js.prefixDKnown = true;
+		js.prefixDFlag = JitState::PREFIX_KNOWN_DIRTY;
 		break;
 	}
-	// TODO: Defer this to end of block
-	MOV(32, M((void *)&mips_->vfpuCtrl[VFPU_CTRL_SPREFIX + regnum]), Imm32(data));
 }
 
 
@@ -114,7 +112,7 @@ void Jit::ApplyPrefixST(u8 *vregs, u32 prefix, VectorSize sz) {
 }
 
 void Jit::ApplyPrefixD(const u8 *vregs, u32 prefix, VectorSize sz, bool onlyWriteMask) {
-	_assert_(js.prefixDKnown);
+	_assert_(js.prefixDFlag & JitState::PREFIX_KNOWN);
 	if (!prefix) return;
 
 	int n = GetNumVectorElements(sz);
@@ -345,6 +343,8 @@ void Jit::Comp_Mftv(u32 op) {
 				gpr.BindToRegister(rt, false, true);
 				MOV(32, gpr.R(rt), fpr.V(imm));
 			} else if (imm < 128 + VFPU_CTRL_MAX) { //mtvc
+				// In case we have a saved prefix.
+				FlushAll();
 				gpr.BindToRegister(rt, false, true);
 				MOV(32, gpr.R(rt), M(&currentMIPS->vfpuCtrl[imm - 128]));
 			} else {
@@ -366,11 +366,11 @@ void Jit::Comp_Mftv(u32 op) {
 
 			// TODO: Optimization if rt is Imm?
 			if (imm - 128 == VFPU_CTRL_SPREFIX) {
-				js.prefixSKnown = false;
+				js.prefixSFlag = JitState::PREFIX_UNKNOWN;
 			} else if (imm - 128 == VFPU_CTRL_TPREFIX) {
-				js.prefixTKnown = false;
+				js.prefixTFlag = JitState::PREFIX_UNKNOWN;
 			} else if (imm - 128 == VFPU_CTRL_DPREFIX) {
-				js.prefixDKnown = false;
+				js.prefixDFlag = JitState::PREFIX_UNKNOWN;
 			}
 		} else {
 			//ERROR
@@ -393,11 +393,11 @@ void Jit::Comp_Vmtvc(u32 op) {
 		fpr.ReleaseSpillLocks();
 
 		if (imm - 128 == VFPU_CTRL_SPREFIX) {
-			js.prefixSKnown = false;
+			js.prefixSFlag = JitState::PREFIX_UNKNOWN;
 		} else if (imm - 128 == VFPU_CTRL_TPREFIX) {
-			js.prefixTKnown = false;
+			js.prefixTFlag = JitState::PREFIX_UNKNOWN;
 		} else if (imm - 128 == VFPU_CTRL_DPREFIX) {
-			js.prefixDKnown = false;
+			js.prefixDFlag = JitState::PREFIX_UNKNOWN;
 		}
 	}
 }
diff --git a/Core/MIPS/x86/Jit.cpp b/Core/MIPS/x86/Jit.cpp
index dc6a789830..24a3000f11 100644
--- a/Core/MIPS/x86/Jit.cpp
+++ b/Core/MIPS/x86/Jit.cpp
@@ -109,6 +109,34 @@ void Jit::FlushAll()
 {
 	gpr.Flush();
 	fpr.Flush();
+	FlushPrefixV();
+}
+
+void Jit::FlushPrefixV()
+{
+	if ((js.prefixSFlag & JitState::PREFIX_DIRTY) != 0)
+	{
+		MOV(32, M((void *)&mips_->vfpuCtrl[VFPU_CTRL_SPREFIX]), Imm32(js.prefixS));
+		js.prefixSFlag = (JitState::PrefixState) (js.prefixSFlag & ~JitState::PREFIX_DIRTY);
+	}
+
+	if ((js.prefixTFlag & JitState::PREFIX_DIRTY) != 0)
+	{
+		MOV(32, M((void *)&mips_->vfpuCtrl[VFPU_CTRL_TPREFIX]), Imm32(js.prefixT));
+		js.prefixTFlag = (JitState::PrefixState) (js.prefixTFlag & ~JitState::PREFIX_DIRTY);
+	}
+
+	if ((js.prefixDFlag & JitState::PREFIX_DIRTY) != 0)
+	{
+		MOV(32, M((void *)&mips_->vfpuCtrl[VFPU_CTRL_DPREFIX]), Imm32(js.prefixD));
+
+		_dbg_assert_msg_(JIT, sizeof(bool) <= 4, "Bools shouldn't be that big?");
+		const size_t bool_stride = 4 / sizeof(bool);
+		for (size_t i = 0; i < ARRAY_SIZE(mips_->vfpuWriteMask); i += bool_stride)
+			MOV(32, M((void *)&mips_->vfpuWriteMask[i]), Imm32(*(u32 *)&js.writeMask[i]));
+
+		js.prefixDFlag = (JitState::PrefixState) (js.prefixDFlag & ~JitState::PREFIX_DIRTY);
+	}
 }
 
 void Jit::WriteDowncount(int offset)
diff --git a/Core/MIPS/x86/Jit.h b/Core/MIPS/x86/Jit.h
index e39b93868e..080375ba7b 100644
--- a/Core/MIPS/x86/Jit.h
+++ b/Core/MIPS/x86/Jit.h
@@ -48,6 +48,14 @@ struct JitOptions
 
 struct JitState
 {
+	enum PrefixState
+	{
+		PREFIX_UNKNOWN = 0x00,
+		PREFIX_KNOWN = 0x01,
+		PREFIX_DIRTY = 0x10,
+		PREFIX_KNOWN_DIRTY = 0x11,
+	};
+
 	u32 compilerPC;
 	u32 blockStart;
 	bool cancel;
@@ -62,22 +70,28 @@ struct JitState
 	u32 prefixT;
 	u32 prefixD;
 	bool writeMask[4];
-	bool prefixSKnown;
-	bool prefixTKnown;
-	bool prefixDKnown;
+	PrefixState prefixSFlag;
+	PrefixState prefixTFlag;
+	PrefixState prefixDFlag;
 	void PrefixStart() {
-		prefixSKnown = false;
-		prefixTKnown = false;
-		prefixDKnown = false;
+		prefixSFlag = PREFIX_UNKNOWN;
+		prefixTFlag = PREFIX_UNKNOWN;
+		prefixDFlag = PREFIX_UNKNOWN;
 	}
 	void EatPrefix() {
-		prefixSKnown = true;
-		prefixTKnown = true;
-		prefixDKnown = true;
-		prefixS = 0xE4;
-		prefixT = 0xE4;
-		prefixD = 0x0;
-		writeMask[0] = writeMask[1] = writeMask[2] = writeMask[3] = false;
+		if ((prefixSFlag & PREFIX_KNOWN) == 0 || prefixS != 0xE4) {
+			prefixSFlag = PREFIX_KNOWN_DIRTY;
+			prefixS = 0xE4;
+		}
+		if ((prefixTFlag & PREFIX_KNOWN) == 0 || prefixT != 0xE4) {
+			prefixTFlag = PREFIX_KNOWN_DIRTY;
+			prefixT = 0xE4;
+		}
+		if ((prefixDFlag & PREFIX_KNOWN) == 0 || prefixD != 0x0 || writeMask[0] || writeMask[1] || writeMask[2] || writeMask[3]) {
+			prefixDFlag = PREFIX_KNOWN_DIRTY;
+			prefixD = 0x0;
+			writeMask[0] = writeMask[1] = writeMask[2] = writeMask[3] = false;
+		}
 	}
 };
 
@@ -155,6 +169,7 @@ public:
 	void ClearCacheAt(u32 em_address);
 private:
 	void FlushAll();
+	void FlushPrefixV();
 	void WriteDowncount(int offset = 0);
 
 	// See CompileDelaySlotFlags for flags.