diff --git a/Foundation/include/Poco/Dynamic/VarHolder.h b/Foundation/include/Poco/Dynamic/VarHolder.h
index f6987b283a..9704f67567 100644
--- a/Foundation/include/Poco/Dynamic/VarHolder.h
+++ b/Foundation/include/Poco/Dynamic/VarHolder.h
@@ -416,7 +416,7 @@ class Foundation_API VarHolder
 			throw RangeException("Value too large.");
 		}
 		else
-		if (from > std::numeric_limits<T>::max())
+		if (from > static_cast<F>(std::numeric_limits<T>::max()))
 		{
 			throw RangeException("Value too large.");
 		}
@@ -457,7 +457,7 @@ class Foundation_API VarHolder
 	template <typename F, typename T>
 	void checkLowerLimit(const F& from) const
 	{
-		if (from < std::numeric_limits<T>::min())
+		if (from < static_cast<F>(std::numeric_limits<T>::min()))
 			throw RangeException("Value too small.");
 	}
 };