TBigInt allocates twice as much memory as necessary for FString input

TBigInt appears to allocate twice as much memory as necessary for the input. This produces an unexpected output of the input value.

1. Open UE4 Editor (Any project)
2. Add code to project based on Actor (MyActor)
3. In MyActor.cpp add the following to the BeginPlay function

TBigInt<128> TestBigInt("12345");
UE_LOG(LogTemp, Warning, TEXT("%s"), *TestBigInt.ToString());

4. Compile code
5. Add instance of the class to the editor
6. Open the Output log and play in editor

Result:
Output log will show the value of TestBigInt as 0x0000000100002345

Expected:
TestBigInt output to appear as 0x12345