diff -aruN a/nandtest.c b/nandtest.c
--- a/nandtest.c	2011-11-16 11:20:33.715549264 -0800
+++ b/nandtest.c	2011-11-16 11:20:46.135549260 -0800
@@ -4,6 +4,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -37,6 +38,9 @@
 int markbad=0;
 int seed;
 
+/*
+ * Erase and write block by block, checking for errors
+ */
 int erase_and_write(loff_t ofs, unsigned char *data, unsigned char *rbuf)
 {
 	struct erase_info_user er;
@@ -126,6 +130,71 @@
 	return 0;
 }
 
+/*
+ * Restore page by page, skipping empty writes (writing all 0xff can result in non-0xff
+ * OOB bytes in empty blocks, which will be a problem for the fs after the test is complete).
+ */
+int erase_and_restore(loff_t ofs, unsigned char *data)
+{
+    struct erase_info_user er;
+    ssize_t len;
+    int page;
+    int page_count = (meminfo.erasesize/meminfo.writesize);
+    int i;
+    bool isempty;
+    unsigned char *data_page = data;
+
+    printf("\r%08x: erasing... ", (unsigned)ofs);
+    fflush(stdout);
+
+    er.start = ofs;
+    er.length = meminfo.erasesize;
+
+    /* Erase the whole block */
+    if (ioctl(fd, MEMERASE, &er)) {
+        perror("MEMERASE");
+        if (markbad) {
+            printf("Mark block bad at %08lx\n", (long)ofs);
+            ioctl(fd, MEMSETBADBLOCK, &ofs);
+	}
+	return 1;
+    }
+
+    printf("\r%08x: writing...", (unsigned)ofs);
+    fflush(stdout);
+
+    /* Write back page by page */
+    for (page = 0; page < page_count; page++, data_page += meminfo.writesize, ofs += meminfo.writesize) {        
+        isempty = true;
+        for (i = 0; i < meminfo.writesize; i++) {
+            if (data_page[i] != 0xff) {
+                isempty = false;
+                break;
+            }
+        }
+
+        if (isempty == false) {
+            len = pwrite(fd, data_page, meminfo.writesize, ofs);
+
+            if (len < 0) {
+                printf("\n");
+                perror("write");
+                if (markbad) {
+                    printf("Mark block bad at %08lx\n", (long)ofs);
+                    ioctl(fd, MEMSETBADBLOCK, &ofs);
+                }
+                return 1;
+            }
+            if (len < meminfo.writesize) {
+                printf("\n");
+                fprintf(stderr, "Short write (%zd bytes)\n", len);
+                exit(1);
+            }
+        }
+    }
+
+    return 0;
+}
 
 /*
  * Main program
@@ -226,7 +295,7 @@
 	wbuf = malloc(meminfo.erasesize * 3);
 	if (!wbuf) {
 		fprintf(stderr, "Could not allocate %d bytes for buffer\n",
-			meminfo.erasesize * 2);
+			meminfo.erasesize * 3);
 		exit(1);
 	}
 	rbuf = wbuf + meminfo.erasesize;
@@ -277,7 +346,7 @@
 			if (erase_and_write(test_ofs, wbuf, rbuf))
 				continue;
 			if (keep_contents)
-				erase_and_write(test_ofs, kbuf, rbuf);
+				erase_and_restore(test_ofs, kbuf);
 		}
 		printf("\nFinished pass %d successfully\n", pass+1);
 	}