Hi, I found (use-modules (rnrs io ports)) (define v (call-with-input-file "EIVE01.DAT" (lambda (port) > (get-bytevector-n port (* 5 1024 1024 1024))))) > fails due to 'out of range': ERROR: In procedure get-bytevector-n: ERROR: Value out of range 0 to 4294967295: 52434042880 The "count" variable was of "unsigned" type (i.e. 32-bit) so I changed it to "size_t" and the problem is solved. Enclosed is the corresponding patch (using format-patch) Jan Ć mydke