The quote, "I was a drum major for justice, peace and righteousness," was an abridgment of a speech King delivered to the congregation of Atlanta's Ebenezer Baptist Church two months before his assassination in 1968, The Washington Post reported.
In that speech, he imagined his own eulogy.
"Yes, if you want to say that I was a drum major, say that I was a drum major for justice," King said. "Say that I was a drum major for peace. I was a drum major for righteousness. And all of the other shallow things will not matter."
Author Maya Angelou criticized the shortening of the quote after the memorial's unveiling August 2011, saying it made King sound like an "arrogant twit."
The Interior Department said the inscription will be removed, not replaced, in order to preserve the "structural integrity" of the three-story statue.
The work is expected to cost between $700,000 and $900,000, and will be paid for by a special fund for the memorial foundation. Work will begin in February or March and should be completed sometime in 2013, the Post reported.