My wife did not work during 2018, but I had money for Dependent Care Benefits in Box 10 on my W2

My wife did not work during 2018, but I had money for Dependent Care Benefits in Box 10 on my W2.  Since she did not work, the system is not letting me put in any information about the preschool.  I don't expect to get any Dependent Care Credit, but figured that the Dependent Care Benefits, which were spent on my child's preschool, would not be taxed.  Am I wrong about my understanding of Dependent Care Benefits FSAs?  If not, how do I enter this into TurboTax so that I don't pay taxes on that additional amount?