--- a/src/iterator.c
+++ b/src/iterator.c
@@ -29,6 +29,8 @@
  */
 
 #include <sys/types.h>
+#include <stdio.h>
+#include <stdlib.h>
 
 #include "config.h"
 
@@ -53,6 +55,10 @@
 int
 iterator_next(iterator *iter, bitmap *bitmap)
 {
+	if (iter->skipmod == 0) {
+		fprintf(stderr, "AUDIT_INVALID_ITERATOR skipmod=0 offset=%d usable_bits=%d\n", iter->off, bitmap->bits);
+		exit(2);
+	}
 	iter->off += (arc4_getword(&iter->as) % iter->skipmod) + 1;
 
 	return iter->off;
--- a/src/outguess.c
+++ b/src/outguess.c
@@ -344,6 +344,10 @@
 	u_int32_t tmp = 0;
 
 	for (where = 0; where < bits; where++) {
+		if (i >= (u_int32_t)bitmap->bits) {
+			fprintf(stderr, "AUDIT_INVALID_READ offset=%u usable_bits=%d\n", i, bitmap->bits);
+			exit(2);
+		}
 		tmp |= (TEST_BIT(bitmap->bitmap, i) ? 1 : 0) << where;
 
 		i = iterator_next(iter, bitmap);
@@ -372,6 +376,9 @@
 	for (i = 0; i < datalen; i++)
 		tmpbuf[i] = steg_retrbyte(bitmap, 8, iter);
 
+	fprintf(stderr, "AUDIT_RAW_HEADER ");
+	for (i = 0; i < datalen; i++) fprintf(stderr, "%02x", tmpbuf[i]);
+	fprintf(stderr, "\n");
 	buf = decode_data (tmpbuf, &datalen, as, flags);
 
 	if (datalen != 4) {
@@ -402,6 +409,8 @@
 	n = 0;
 	while (datalen > 0) {
 		iterator_adapt(iter, bitmap, datalen);
+		if (iter->skipmod == 0)
+			fprintf(stderr, "AUDIT_REMAINING bytes=%u completed=%u\n", datalen, n);
 		buf[n++] = steg_retrbyte(bitmap, 8, iter);
 		datalen --;
 	}