Remeber the USCIS will correct I-94 in which they did mistake. If you did mistake then you have to go to Custom Border Protection Office. You can go to nearest CBP office or port of entry. Follow the link provided above thread. You can have all infomration including which local office handles what. It may not be necessary that you need to go to port of entry. You call CPB office at appropriate location for you and take an appointment. Take your passport and I-94. They will correct and stamp. Never make correction on govt documents yourself. Also the data on govt system should also be correct. If the information on your I-94 and data system doesnot match, you will have trouble in future. Also remember DOB is very vital data in US.

One more thing, it does not cost a penny to make correction on I-94 from CPB office except gas cost to go there.

This suggestion is from my experience as I had my parents I-94 get correct at local office as they had similar error like yours.