diff --git a/src/Pipeline/SpirvID.hpp b/src/Pipeline/SpirvID.hpp
index 67ca59d..e90a8cc 100644
--- a/src/Pipeline/SpirvID.hpp
+++ b/src/Pipeline/SpirvID.hpp
@@ -15,6 +15,8 @@
 #ifndef sw_ID_hpp
 #define sw_ID_hpp
 
+#include "System/Debug.hpp"
+
 #include <cstdint>
 #include <unordered_map>
 
@@ -31,15 +33,16 @@
 public:
 	SpirvID() = default;
 	inline SpirvID(uint32_t id);
+
 	inline bool operator==(const SpirvID<T> &rhs) const;
 	inline bool operator!=(const SpirvID<T> &rhs) const;
 	inline bool operator<(const SpirvID<T> &rhs) const;
 
-	// value returns the numerical value of the identifier.
+	// Returns the numerical value of the identifier.
 	inline uint32_t value() const;
 
 private:
-	uint32_t id = 0;
+	uint32_t id = 0;  // Valid ids are in the range "0 < id < Bound".
 };
 
 template<typename T>
@@ -68,6 +71,10 @@
 template<typename T>
 uint32_t SpirvID<T>::value() const
 {
+	// Assert that we don't attempt to use unassigned IDs.
+	// Use if(id != 0) { ... } to avoid invalid code paths.
+	ASSERT(id != 0);
+
 	return id;
 }
 
diff --git a/src/Pipeline/SpirvShader.cpp b/src/Pipeline/SpirvShader.cpp
index c56fd38..6239a20 100644
--- a/src/Pipeline/SpirvShader.cpp
+++ b/src/Pipeline/SpirvShader.cpp
@@ -207,7 +207,7 @@
 
 		case spv::OpLabel:
 			{
-				ASSERT(currentBlock.value() == 0);
+				ASSERT(currentBlock == 0);
 				currentBlock = Block::ID(insn.word(1));
 				blockStart = insn;
 			}
@@ -224,8 +224,8 @@
 		case spv::OpKill:
 		case spv::OpUnreachable:
 			{
-				ASSERT(currentBlock.value() != 0);
-				ASSERT(currentFunction.value() != 0);
+				ASSERT(currentBlock != 0);
+				ASSERT(currentFunction != 0);
 
 				auto blockEnd = insn;
 				blockEnd++;
diff --git a/src/Pipeline/SpirvShaderControlFlow.cpp b/src/Pipeline/SpirvShaderControlFlow.cpp
index 7893023..754e91d 100644
--- a/src/Pipeline/SpirvShaderControlFlow.cpp
+++ b/src/Pipeline/SpirvShaderControlFlow.cpp
@@ -778,6 +778,7 @@
 					     << "[label=\"M\" style=dashed color=blue]"
 					     << std::endl;
 				}
+
 				if(block.second.continueTarget != 0)
 				{
 					file << "    block_" << block.first.value() << " -> "
diff --git a/src/Pipeline/SpirvShaderImage.cpp b/src/Pipeline/SpirvShaderImage.cpp
index d13ed5a..426b087 100644
--- a/src/Pipeline/SpirvShaderImage.cpp
+++ b/src/Pipeline/SpirvShaderImage.cpp
@@ -557,7 +557,7 @@
 	}
 
 	SIMD::Int n = 0;
-	if(sampleId.value())
+	if(sampleId != 0)
 	{
 		Operand sample(this, state, sampleId);
 		if(!sample.isConstantZero())
@@ -587,7 +587,7 @@
 			oobMask |= As<SIMD::Int>(CmpNLT(As<SIMD::UInt>(w), SIMD::UInt(depth)));
 		}
 
-		if(sampleId.value())
+		if(sampleId != 0)
 		{
 			Operand sample(this, state, sampleId);
 			if(!sample.isConstantZero())