diff --git a/src/CalculatorUnitTests/HistoryTests.cpp b/src/CalculatorUnitTests/HistoryTests.cpp
index a74245c0..ec1220b5 100644
--- a/src/CalculatorUnitTests/HistoryTests.cpp
+++ b/src/CalculatorUnitTests/HistoryTests.cpp
@@ -83,7 +83,7 @@ namespace CalculatorFunctionalTests
         void AddSingleHistoryItem()
         {
             Initialize();
-            size_r initialSize = m_historyViewModel->ItemsCount;
+            size_t initialSize = m_historyViewModel->ItemsCount;
             m_standardViewModel->SendCommandToCalcManager(static_cast<int>(Command::Command1));
             m_standardViewModel->SendCommandToCalcManager(static_cast<int>(Command::CommandADD));
             m_standardViewModel->SendCommandToCalcManager(static_cast<int>(Command::Command8));