diff --git a/src/OpenGL/compiler/OutputASM.cpp b/src/OpenGL/compiler/OutputASM.cpp
index 5a8bcdf..308da1a 100644
--- a/src/OpenGL/compiler/OutputASM.cpp
+++ b/src/OpenGL/compiler/OutputASM.cpp
@@ -1859,6 +1859,11 @@
 		if(loop.isDeterministic())
 		{
 			 deterministicVariables.insert(loop.index->getId());
+
+			 if(!unroll)
+			 {
+				 emit(sw::Shader::OPCODE_SCALAR);   // Unrolled loops don't have an ENDWHILE to disable scalar mode.
+			 }
 		}
 
 		if(node->getType() == ELoopDoWhile)
@@ -1926,6 +1931,11 @@
 
 				emit(sw::Shader::OPCODE_TEST);
 
+				if(loop.isDeterministic())
+				{
+					emit(sw::Shader::OPCODE_SCALAR);
+				}
+
 				if(expression)
 				{
 					expression->traverse(this);
diff --git a/src/Shader/PixelProgram.cpp b/src/Shader/PixelProgram.cpp
index ec0bba0..7dff00b 100644
--- a/src/Shader/PixelProgram.cpp
+++ b/src/Shader/PixelProgram.cpp
@@ -310,6 +310,7 @@
 			case Shader::OPCODE_BREAKP:     BREAKP(src0);                                  break;
 			case Shader::OPCODE_CONTINUE:   CONTINUE();                                    break;
 			case Shader::OPCODE_TEST:       TEST();                                        break;
+			case Shader::OPCODE_SCALAR:     SCALAR();                                      break;
 			case Shader::OPCODE_CALL:       CALL(dst.label, dst.callSite);                 break;
 			case Shader::OPCODE_CALLNZ:     CALLNZ(dst.label, dst.callSite, src0);         break;
 			case Shader::OPCODE_ELSE:       ELSE();                                        break;
@@ -832,6 +833,11 @@
 
 	Int4 PixelProgram::enableMask(const Shader::Instruction *instruction)
 	{
+		if(scalar)
+		{
+			return Int4(0xFFFFFFFF);
+		}
+
 		Int4 enable = instruction->analysisBranch ? Int4(enableStack[enableIndex]) : Int4(0xFFFFFFFF);
 
 		if(shader->containsBreakInstruction() && instruction->analysisBreak)
@@ -1396,6 +1402,11 @@
 		restoreContinue.pop_back();
 	}
 
+	void PixelProgram::SCALAR()
+	{
+		scalar = true;
+	}
+
 	void PixelProgram::CALL(int labelIndex, int callSiteIndex)
 	{
 		if(!labelBlock[labelIndex])
@@ -1572,6 +1583,7 @@
 		Nucleus::setInsertBlock(endBlock);
 
 		enableIndex--;
+		scalar = false;
 	}
 
 	void PixelProgram::ENDSWITCH()
@@ -1777,6 +1789,7 @@
 		Nucleus::setInsertBlock(loopBlock);
 
 		loopRepDepth++;
+		scalar = false;
 	}
 
 	void PixelProgram::SWITCH()
diff --git a/src/Shader/PixelProgram.hpp b/src/Shader/PixelProgram.hpp
index 0f628bc..3c3a06f 100644
--- a/src/Shader/PixelProgram.hpp
+++ b/src/Shader/PixelProgram.hpp
@@ -24,14 +24,14 @@
 	{
 	public:
 		PixelProgram(const PixelProcessor::State &state, const PixelShader *shader) :
-			PixelRoutine(state, shader), r(shader->indirectAddressableTemporaries),
-			loopDepth(-1), ifDepth(0), loopRepDepth(0), currentLabel(-1)
+			PixelRoutine(state, shader), r(shader->indirectAddressableTemporaries)
 		{
 			for(int i = 0; i < 2048; ++i)
 			{
 				labelBlock[i] = 0;
 			}
 
+			loopDepth = -1;
 			enableStack[0] = Int4(0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF);
 
 			if(shader->containsBreakInstruction())
@@ -129,6 +129,7 @@
 		void BREAK(Int4 &condition);
 		void CONTINUE();
 		void TEST();
+		void SCALAR();
 		void CALL(int labelIndex, int callSiteIndex);
 		void CALLNZ(int labelIndex, int callSiteIndex, const Src &src);
 		void CALLNZb(int labelIndex, int callSiteIndex, const Src &boolRegister);
@@ -152,9 +153,10 @@
 		void RET();
 		void LEAVE();
 
-		int ifDepth;
-		int loopRepDepth;
-		int currentLabel;
+		int ifDepth = 0;
+		int loopRepDepth = 0;
+		int currentLabel = -1;
+		bool scalar = false;
 
 		BasicBlock *ifFalseBlock[24 + 24];
 		BasicBlock *loopRepTestBlock[4];
diff --git a/src/Shader/Shader.hpp b/src/Shader/Shader.hpp
index 9e4a810..ada88ba 100644
--- a/src/Shader/Shader.hpp
+++ b/src/Shader/Shader.hpp
@@ -244,9 +244,10 @@
 			OPCODE_INSERT,
 			OPCODE_DISCARD,
 			OPCODE_FWIDTH,
-			OPCODE_LEAVE,   // Return before the end of the function
+			OPCODE_LEAVE,    // Return before the end of the function
 			OPCODE_CONTINUE,
-			OPCODE_TEST,   // Marks the end of the code that can be skipped by 'continue'
+			OPCODE_TEST,     // Marks the end of the code that can be skipped by 'continue'
+			OPCODE_SCALAR,   // Marks the start of code not subject to SIMD lane masking. Ends at WHILE and ENDWHILE.
 			OPCODE_SWITCH,
 			OPCODE_ENDSWITCH,
 
diff --git a/src/Shader/VertexProgram.cpp b/src/Shader/VertexProgram.cpp
index d492c65..55cc8c8 100644
--- a/src/Shader/VertexProgram.cpp
+++ b/src/Shader/VertexProgram.cpp
@@ -26,10 +26,6 @@
 	VertexProgram::VertexProgram(const VertexProcessor::State &state, const VertexShader *shader)
 		: VertexRoutine(state, shader), shader(shader), r(shader->indirectAddressableTemporaries)
 	{
-		ifDepth = 0;
-		loopRepDepth = 0;
-		currentLabel = -1;
-
 		for(int i = 0; i < 2048; i++)
 		{
 			labelBlock[i] = 0;
@@ -295,6 +291,7 @@
 			case Shader::OPCODE_BREAKP:     BREAKP(src0);                   break;
 			case Shader::OPCODE_CONTINUE:   CONTINUE();                     break;
 			case Shader::OPCODE_TEST:       TEST();                         break;
+			case Shader::OPCODE_SCALAR:     SCALAR();                       break;
 			case Shader::OPCODE_CALL:       CALL(dst.label, dst.callSite);  break;
 			case Shader::OPCODE_CALLNZ:     CALLNZ(dst.label, dst.callSite, src0); break;
 			case Shader::OPCODE_ELSE:       ELSE();                         break;
@@ -977,6 +974,11 @@
 
 	Int4 VertexProgram::enableMask(const Shader::Instruction *instruction)
 	{
+		if(scalar)
+		{
+			return Int4(0xFFFFFFFF);
+		}
+
 		Int4 enable = instruction->analysisBranch ? Int4(enableStack[enableIndex]) : Int4(0xFFFFFFFF);
 
 		if(shader->containsBreakInstruction() && instruction->analysisBreak)
@@ -1108,6 +1110,11 @@
 		restoreContinue.pop_back();
 	}
 
+	void VertexProgram::SCALAR()
+	{
+		scalar = true;
+	}
+
 	void VertexProgram::CALL(int labelIndex, int callSiteIndex)
 	{
 		if(!labelBlock[labelIndex])
@@ -1284,6 +1291,7 @@
 		Nucleus::setInsertBlock(endBlock);
 
 		enableIndex--;
+		scalar = false;
 	}
 
 	void VertexProgram::ENDSWITCH()
@@ -1490,6 +1498,7 @@
 		Nucleus::setInsertBlock(loopBlock);
 
 		loopRepDepth++;
+		scalar = false;
 	}
 
 	void VertexProgram::SWITCH()
diff --git a/src/Shader/VertexProgram.hpp b/src/Shader/VertexProgram.hpp
index 437c881..33f3c5c 100644
--- a/src/Shader/VertexProgram.hpp
+++ b/src/Shader/VertexProgram.hpp
@@ -86,6 +86,7 @@
 		void BREAK(Int4 &condition);
 		void CONTINUE();
 		void TEST();
+		void SCALAR();
 		void CALL(int labelIndex, int callSiteIndex);
 		void CALLNZ(int labelIndex, int callSiteIndex, const Src &src);
 		void CALLNZb(int labelIndex, int callSiteIndex, const Src &boolRegister);
@@ -121,9 +122,10 @@
 		Vector4f sampleTexture(const Src &s, Vector4f &uvwq, Float4 &lod, Vector4f &dsx, Vector4f &dsy, Vector4f &offset, SamplerFunction function);
 		Vector4f sampleTexture(int sampler, Vector4f &uvwq, Float4 &lod, Vector4f &dsx, Vector4f &dsy, Vector4f &offset, SamplerFunction function);
 
-		int ifDepth;
-		int loopRepDepth;
-		int currentLabel;
+		int ifDepth = 0;
+		int loopRepDepth = 0;
+		int currentLabel = -1;
+		bool scalar = false;
 
 		BasicBlock *ifFalseBlock[24 + 24];
 		BasicBlock *loopRepTestBlock[4];