diff --git a/neo/libs/optick/optick_gpu.h b/neo/libs/optick/optick_gpu.h
index a3c83364..8134ca6d 100644
--- a/neo/libs/optick/optick_gpu.h
+++ b/neo/libs/optick/optick_gpu.h
@@ -62,7 +62,7 @@ namespace Optick
 			int64_t GetCPUTimestamp(int64_t gpuTimestamp)
 			{
 				// SRS - Improve accuracy of GPU to CPU timestamp conversion by using floating point doubles
-				return timestampCPU + std::llround(double(gpuTimestamp - timestampGPU) * (double)frequencyCPU / (double)frequencyGPU);
+				return timestampCPU + (int64_t)(double(gpuTimestamp - timestampGPU) * (double)frequencyCPU / (double)frequencyGPU);
 			}
 
 			ClockSynchronization() : frequencyCPU(0), frequencyGPU(0), timestampCPU(0), timestampGPU(0) {}
diff --git a/neo/libs/optick/optick_gpu.vulkan.cpp b/neo/libs/optick/optick_gpu.vulkan.cpp
index 10296d8d..d9ce25b7 100644
--- a/neo/libs/optick/optick_gpu.vulkan.cpp
+++ b/neo/libs/optick/optick_gpu.vulkan.cpp
@@ -452,7 +452,7 @@ namespace Optick
 		clock.frequencyCPU = GetHighPrecisionFrequency();
 		VkPhysicalDeviceProperties Properties;
 		(*vulkanFunctions.vkGetPhysicalDeviceProperties)(nodePayloads[nodeIndex]->physicalDevice, &Properties);
-		clock.frequencyGPU = std::llround(1000000000.0 / (double)Properties.limits.timestampPeriod);
+		clock.frequencyGPU = (int64_t)(1000000000.0 / (double)Properties.limits.timestampPeriod);
 
 		// SRS - Reset entire query pool to clear clock sync query + any leftover queries from previous run
 		(*vulkanFunctions.vkBeginCommandBuffer)(CB, &commandBufferBeginInfo);