diff --git a/libisoburn/isofs_wrap.c b/libisoburn/isofs_wrap.c
index f296859d..5af6668a 100644
--- a/libisoburn/isofs_wrap.c
+++ b/libisoburn/isofs_wrap.c
@@ -675,22 +675,22 @@ int isoburn_invalidate_iso(struct isoburn *o, int flag)
  /* 
   * replace CD001 with CDXX1 in PVM.
   */
- strncpy(head + 16 * 2048 + 1, "CDXX1", 5);
+ memcpy(head + 16 * 2048 + 1, "CDXX1", 5);
 
  /* Invalidate further ECMA-119 volume descriptors and possible UDF volume
     recognition sequence */
  for(i= 17 * 2048; i < 32 * 2048; i+= 2048) {
    if(end_ed_found) {
      if(head[i] == 0 && strncmp(head + i + 1, "BEA01", 5) == 0)
-       strncpy(head + i + 1, "BEAX1", 5);
+       memcpy(head + i + 1, "BEAX1", 5);
      else if(head[i] == 0 && strncmp(head + i + 1, "NSR", 3) == 0)
-       strncpy(head + i + 1, "NSRX", 4);
+       memcpy(head + i + 1, "NSRX", 4);
      else if(head[i] == 0 && strncmp(head + i + 1, "TEA", 3) == 0) 
-       strncpy(head + i + 1, "TEAX", 4);
+       memcpy(head + i + 1, "TEAX", 4);
    } else if(strncmp(head + i + 1, "CD001", 5) == 0) {
      if(((unsigned char *) head)[i] == 0xff)
        end_ed_found= 1;
-     strncpy(head + i + 3, "XX", 2);
+     memcpy(head + i + 3, "XX", 2);
    }
  }