According to Keith Lehrer’s coherence theory, knowledge is true acceptance whose justification is undefeated by a falsehood. It has recently become clear that Lehrer’s handling of important Gettier-inspired problems depends upon his position that only falsehoods accepted by the subject can act as defeaters of knowledge. I argue against this and present an example in which an unreckoned truth---one neither believed nor believed to be false by the subject---defeats knowledge. I trace the negative implications of this matter for the coherence (...) theory. (shrink)