Bug report: Running Stefano's Sudoku example from his cells-doc in Lispworks for Linux 5.1, got an error in record-caller: Error: The subscript 16 exceeds the limit 15 for the first dimension of the array #*1111111111111111. 1 (abort) Return to level 0. 2 Return to top loop level 0. Lispworks said the offending code was at the indicated line: (handler-case (setf (sbit (cd-usage *depender*) used-pos) 1) ; <== ### here ### (type-error (error) (declare (ignorable error)) (setf (cd-usage *depender*) (adjust-array (cd-usage *depender*) (+ used-pos 16) :initial-element 0)) (setf (sbit (cd-usage *depender*) used-pos) 1)))) Fix: The condition reported was of type CONDITIONS:SUBSCRIPT-OUT-OF-BOUNDS. I added that to the handler-case, and then it worked: (handler-case (setf (sbit (cd-usage *depender*) used-pos) 1) ((or type-error conditions:subscript-out-of-bounds) (error) ;^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ (declare (ignorable error)) (setf (cd-usage *depender*) (adjust-array (cd-usage *depender*) (+ used-pos 16) :initial-element 0)) (setf (sbit (cd-usage *depender*) used-pos) 1)))) However, this seems like a demonstrably error-prone way to handle this particular situation, so I got rid of the handler-case entirely and tried this: (let ((cd-usage (cd-usage *depender*))) (when (>= used-pos (array-dimension cd-usage 0)) (setf cd-usage (setf (cd-usage *depender*) (adjust-array (cd-usage *depender*) (+ used-pos 16) :initial-element 0)))) (setf (sbit cd-usage used-pos) 1)) It works, doesn't depend on implementation-specific conditions, and in my limited testing (I ran the sudoku solver three times using each version), seems at least as fast, if not a tiny bit faster. -- Larry