diff --git a/PerfectNumbers.Core/Gpu/MersenneNumberIncrementalGpuTester.cs b/PerfectNumbers.Core/Gpu/MersenneNumberIncrementalGpuTester.cs
index 2f854e5..61bf889 100644
--- a/PerfectNumbers.Core/Gpu/MersenneNumberIncrementalGpuTester.cs
+++ b/PerfectNumbers.Core/Gpu/MersenneNumberIncrementalGpuTester.cs
@@ -16,6 +16,7 @@ public class MersenneNumberIncrementalGpuTester(GpuKernelType kernelType, bool u
 
     public void Scan(ulong exponent, UInt128 twoP, LastDigit lastDigit, UInt128 maxK, ref bool isPrime)
     {
+		// TODO: Replace LastDigit lastDigit with bool lastIsSeven
         throw new NotImplementedException($"GPU incremental scanning requires the device cycle heuristics implementation (kernel: {_kernelType}, GPU order: {_useGpuOrder}).");
 
         // GpuPrimeWorkLimiter.Acquire();
diff --git a/PerfectNumbers.Core/Gpu/MersenneNumberOrderGpuTester.cs b/PerfectNumbers.Core/Gpu/MersenneNumberOrderGpuTester.cs
index d064387..e73d75d 100644
--- a/PerfectNumbers.Core/Gpu/MersenneNumberOrderGpuTester.cs
+++ b/PerfectNumbers.Core/Gpu/MersenneNumberOrderGpuTester.cs
@@ -11,6 +11,7 @@ public class MersenneNumberOrderGpuTester(GpuKernelType kernelType, bool useGpuO
 
 	public void Scan(ulong exponent, UInt128 twoP, LastDigit lastDigit, UInt128 maxK, ref bool isPrime)
 	{
+		// TODO: Replace LastDigit lastDigit with bool lastIsSeven
 		// GpuPrimeWorkLimiter.Acquire();
 		// var accelerator = SharedGpuContext.Accelerator;
 		var acceleratorIndex = AcceleratorPool.Shared.Rent();
diff --git a/PerfectNumbers.Core/Gpu/MersenneNumberResidueGpuTester.cs b/PerfectNumbers.Core/Gpu/MersenneNumberResidueGpuTester.cs
index 997abf3..2b0a716 100644
--- a/PerfectNumbers.Core/Gpu/MersenneNumberResidueGpuTester.cs
+++ b/PerfectNumbers.Core/Gpu/MersenneNumberResidueGpuTester.cs
@@ -26,6 +26,7 @@ public class MersenneNumberResidueGpuTester(bool useGpuOrder)
 	[MethodImpl(MethodImplOptions.AggressiveOptimization)]
 	public void Scan(PrimeOrderCalculatorAccelerator gpu, ulong exponent, UInt128 twoP, LastDigit lastDigit, UInt128 maxK, ref bool isPrime)
 	{
+		// TODO: Replace LastDigit lastDigit with bool lastIsSeven
 		// GpuPrimeWorkLimiter.Acquire();
 		var acceleratorIndex = gpu.AcceleratorIndex;
 		var accelerator = gpu.Accelerator;