diff --git a/extra/inverse/inverse.factor b/extra/inverse/inverse.factor
index a38af644b0..b9e0788192 100755
--- a/extra/inverse/inverse.factor
+++ b/extra/inverse/inverse.factor
@@ -148,7 +148,6 @@ MACRO: undo ( quot -- ) [undo] ;
 
 \ exp [ log ] define-inverse
 \ log [ exp ] define-inverse
-\ not [ not ] define-inverse
 \ sq [ sqrt ] define-inverse
 \ sqrt [ sq ] define-inverse