diff --git a/Core/MIPS/IR/IRCompVFPU.cpp b/Core/MIPS/IR/IRCompVFPU.cpp
index 4c9138fef2..734c81b721 100644
--- a/Core/MIPS/IR/IRCompVFPU.cpp
+++ b/Core/MIPS/IR/IRCompVFPU.cpp
@@ -425,11 +425,11 @@ namespace MIPSComp {
 	void IRFrontend::Comp_VMatrixInit(MIPSOpcode op) {
 		CONDITIONAL_DISABLE(VFPU_XFER);
 		MatrixSize sz = GetMtxSize(op);
-		if (sz != M_4x4) {
+		if (sz != M_4x4 || !js.HasNoPrefix()) {
 			DISABLE;
 		}
 
-		// Matrix init (no prefixes)
+		// Matrix init (weird prefixes)
 		// d[N,M] = CONST[N,M]
 
 		// Not really about trying here, it will work if enabled.
diff --git a/Core/MIPS/MIPSIntVFPU.cpp b/Core/MIPS/MIPSIntVFPU.cpp
index c7e7ca2946..e1cb4c59eb 100644
--- a/Core/MIPS/MIPSIntVFPU.cpp
+++ b/Core/MIPS/MIPSIntVFPU.cpp
@@ -288,24 +288,20 @@ namespace MIPSInt
 		PC += 4;
 	}
 
-	void Int_VMatrixInit(MIPSOpcode op)
-	{
-		static const float idt[16] = 
-		{
+	void Int_VMatrixInit(MIPSOpcode op) {
+		static const float idt[16] = {
 			1,0,0,0,
 			0,1,0,0,
 			0,0,1,0,
 			0,0,0,1,
 		};
-		static const float zero[16] = 
-		{
+		static const float zero[16] = {
 			0,0,0,0,
 			0,0,0,0,
 			0,0,0,0,
 			0,0,0,0,
 		};
-		static const float one[16] = 
-		{
+		static const float one[16] = {
 			1,1,1,1,
 			1,1,1,1,
 			1,1,1,1,
@@ -315,8 +311,7 @@ namespace MIPSInt
 		MatrixSize sz = GetMtxSize(op);
 		const float *m;
 
-		switch ((op >> 16) & 0xF)
-		{
+		switch ((op >> 16) & 0xF) {
 		case 3: m=idt; break; //identity   // vmidt
 		case 6: m=zero; break;             // vmzero
 		case 7: m=one; break;              // vmone
@@ -327,7 +322,25 @@ namespace MIPSInt
 			return;
 		}
 
-		WriteMatrix(m, sz, vd);
+		// The S prefix generates constants, but only for the final (possibly transposed) row.
+		if (currentMIPS->vfpuCtrl[VFPU_CTRL_SPREFIX] & 0xF0F00) {
+			float prefixed[16];
+			memcpy(prefixed, m, sizeof(prefixed));
+
+			int off = GetMatrixSide(sz) - 1;
+			u32 sprefixRemove = VFPU_ANY_SWIZZLE();
+			u32 sprefixAdd = VFPU_CONST(1, 1, 1, 1);
+			switch ((op >> 16) & 0xF) {
+			case 3: sprefixAdd |= VFPU_SWIZZLE(off == 0, off == 1, off == 2, off == 3); break;
+			case 6: sprefixAdd |= VFPU_SWIZZLE(0, 0, 0, 0); break;
+			case 7: sprefixAdd |= VFPU_SWIZZLE(1, 1, 1, 1); break;
+			}
+			ApplyPrefixST(&prefixed[off * 4], VFPURewritePrefix(VFPU_CTRL_SPREFIX, sprefixRemove, sprefixAdd), V_Quad);
+			WriteMatrix(prefixed, sz, vd);
+		} else {
+			// Write mask applies to the final (maybe transposed) row.  Sat causes hang.
+			WriteMatrix(m, sz, vd);
+		}
 		PC += 4;
 		EatPrefixes();
 	}