diff --git a/bochs/doc/docbook/user/user.dbk b/bochs/doc/docbook/user/user.dbk
index 420fffdd8..1844f46d1 100644
--- a/bochs/doc/docbook/user/user.dbk
+++ b/bochs/doc/docbook/user/user.dbk
@@ -8735,12 +8735,12 @@ Other arguments:
   <row>
     <entry>concat</entry>
     <entry>Create only</entry>
-    <entry>No</entry>
+    <entry>Convert source only</entry>
   </row>
   <row>
     <entry>dll</entry>
     <entry>No</entry>
-    <entry>No</entry>
+    <entry>Convert source only</entry>
   </row>
   <row>
     <entry>sparse</entry>
@@ -8771,6 +8771,11 @@ Other arguments:
 </tgroup>
 </table>
 </para>
+<para>
+Disk image mode autodetection does not work for the modes <emphasis>concat</emphasis>
+and <emphasis>dll</emphasis>. To use those images as convert source, you have to
+add a prefix ("concat:" or "dll:") to the image path.
+</para>
 <section><title>Create image</title>
 <para>
 This function can be used to create several disk image formats for the
diff --git a/bochs/iodev/hdimage/hdimage.cc b/bochs/iodev/hdimage/hdimage.cc
index 1e7520c71..05818ffc5 100644
--- a/bochs/iodev/hdimage/hdimage.cc
+++ b/bochs/iodev/hdimage/hdimage.cc
@@ -515,7 +515,7 @@ char increment_string(char *str, int diff)
   p--;  // point to last character of the string
   (*p) += diff;  // increment to next/previous ascii code.
   BX_DEBUG(("increment string returning '%s'", str));
- return (*p);
+  return (*p);
 }
 
 /*** concat_image_t function definitions ***/
@@ -527,7 +527,7 @@ concat_image_t::concat_image_t()
 
 void concat_image_t::increment_string(char *str)
 {
- ::increment_string(str, +1);
+  ::increment_string(str, +1);
 }
 
 int concat_image_t::open(const char* _pathname0, int flags)
@@ -535,7 +535,7 @@ int concat_image_t::open(const char* _pathname0, int flags)
   UNUSED(flags);
   pathname0 = _pathname0;
   char *pathname = strdup(pathname0);
-  BX_DEBUG(("concat_image_t.open"));
+  BX_DEBUG(("concat_image_t::open"));
   Bit64s start_offset = 0;
   for (int i=0; i<BX_CONCAT_MAX_IMAGES; i++) {
     fd_table[i] = ::open(pathname, O_RDWR
@@ -580,6 +580,7 @@ int concat_image_t::open(const char* _pathname0, int flags)
   thismax = length_table[0]-1;
   seek_was_last_op = 0;
   hd_size = start_offset;
+  BX_INFO(("hd_size: "FMT_LL"u", hd_size));
   return 0; // success.
 }
 
diff --git a/bochs/misc/bximage.cc b/bochs/misc/bximage.cc
index 8b1fb385a..648c25383 100644
--- a/bochs/misc/bximage.cc
+++ b/bochs/misc/bximage.cc
@@ -334,6 +334,16 @@ device_image_t* init_image(Bit8u image_mode)
       hdimage = new default_image_t();
       break;
 
+    case BX_HDIMAGE_MODE_CONCAT:
+      hdimage = new concat_image_t();
+      break;
+
+#ifdef WIN32
+    case BX_HDIMAGE_MODE_DLL_HD:
+      hdimage = new dll_image_t();
+      break;
+#endif
+
     case BX_HDIMAGE_MODE_SPARSE:
       hdimage = new sparse_image_t();
       break;
@@ -610,13 +620,27 @@ void create_hard_disk_image(const char *filename, int imgmode, Bit64u size)
 void convert_image(int newimgmode, Bit64u newsize)
 {
   device_image_t *source_image, *dest_image;
+  int mode = -1;
   Bit64u i, sc, s;
   char buffer[512], null_sector[512];
   bx_bool error = 0;
 
   printf("\n");
   memset(null_sector, 0, 512);
-  int mode = hdimage_detect_image_mode(bx_filename_1);
+  if (newsize == 0) {
+    if (!strncmp(bx_filename_1, "concat:", 7)) {
+      mode = BX_HDIMAGE_MODE_CONCAT;
+      strcpy(bx_filename_1, &bx_filename_1[7]);
+#ifdef WIN32
+    } else if (!strncmp(bx_filename_1, "dll:", 4)) {
+      mode = BX_HDIMAGE_MODE_DLL_HD;
+      strcpy(bx_filename_1, &bx_filename_1[4]);
+#endif
+    }
+  }
+  if (mode == -1) {
+    mode = hdimage_detect_image_mode(bx_filename_1);
+  }
   if (mode == BX_HDIMAGE_MODE_UNKNOWN)
     fatal("source disk image mode not detected");
 
@@ -969,7 +993,7 @@ int main(int argc, char *argv[])
         if (ask_string("\nWhat is the name of the source image?\n", bx_filename_1, bx_filename_1) < 0)
           fatal(EOF_ERR);
         if (!strlen(bx_filename_2)) {
-          strcpy(tmpfname, "c-new.img");
+          strcpy(tmpfname, bx_filename_1);
         } else {
           strcpy(tmpfname, bx_filename_2);
         }
@@ -989,7 +1013,7 @@ int main(int argc, char *argv[])
         if (ask_string("\nWhat is the name of the source image?\n", bx_filename_1, bx_filename_1) < 0)
           fatal(EOF_ERR);
         if (!strlen(bx_filename_2)) {
-          strcpy(tmpfname, "c-new.img");
+          strcpy(tmpfname, bx_filename_1);
         } else {
           strcpy(tmpfname, bx_filename_2);
         }
@@ -1035,13 +1059,17 @@ int main(int argc, char *argv[])
           printf("\nCreating floppy image '%s' with %d sectors\n", bx_filename_1, fdsize_sectors[bx_fdsize_idx]);
           create_flat_image(bx_filename_1, fdsize_sectors[bx_fdsize_idx] * 512);
         } else {
+          int heads = 16, spt = 63;
+
           sprintf(bochsrc_line, "ata0-master: type=disk, path=\"%s\", mode=%s", bx_filename_1, hdmode_choices[bx_imagemode]);
           imgmode = hdmode_choice_id[bx_imagemode];
           hdsize = ((Bit64u)bx_hdsize) << 20;
           Bit64u cyl = (Bit64u)(hdsize/16.0/63.0/512.0);
           if (cyl >= (1 << BX_MAX_CYL_BITS))
             fatal("ERROR: number of cylinders out of range !\n");
-          printf("\nCreating hard disk image '%s' with CHS=%ld/16/63\n", bx_filename_1, cyl);
+          printf("\nCreating hard disk image '%s' with CHS=%ld/%d/%d\n", bx_filename_1,
+                 cyl, heads, spt);
+          hdsize = cyl * heads * spt * 512;
           create_hard_disk_image(bx_filename_1, imgmode, hdsize);
         }
         printf("\nThe following line should appear in your bochsrc:\n");