diff --git a/daemon/devsparts.c b/daemon/devsparts.c
index b6f755beb..8020fbe14 100644
--- a/daemon/devsparts.c
+++ b/daemon/devsparts.c
@@ -241,3 +241,26 @@ do_part_to_partnum (const char *part)
 
   return r;
 }
+
+int
+do_device_index (const char *device)
+{
+  char **devices;
+  size_t i;
+  int ret = -1;
+
+  devices = do_list_devices ();
+  if (devices == NULL)
+    return -1;
+
+  for (i = 0; devices[i] != NULL; ++i) {
+    if (STREQ (device, devices[i]))
+      ret = (int) i;
+    free (devices[i]);
+  }
+  free (devices);
+
+  if (ret == -1)
+    reply_with_error ("device not found");
+  return ret;
+}
diff --git a/generator/generator_actions.ml b/generator/generator_actions.ml
index 7b2bd97f8..f249991e8 100644
--- a/generator/generator_actions.ml
+++ b/generator/generator_actions.ml
@@ -6062,7 +6062,7 @@ removes the partition number, returning the device name
 The named partition must exist, for example as a string returned
 from C<guestfs_list_partitions>.
 
-See also C<guestfs_part_to_partnum>.");
+See also C<guestfs_part_to_partnum>, C<guestfs_device_index>.");
 
   ("upload_offset", (RErr, [FileIn "filename"; Dev_or_Path "remotefilename"; Int64 "offset"], []), 273,
    [Progress; Cancellable],
@@ -7323,6 +7323,19 @@ different operation that turns free space in the filesystem
 into zeroes.  It is valid to call C<guestfs_fstrim> either
 instead of, or after calling C<guestfs_zero_free_space>.");
 
+  ("device_index", (RInt "index", [Device "device"], []), 335, [],
+   [InitEmpty, Always, TestOutputInt (
+      [["device_index"; "/dev/sda"]], 0)],
+   "convert device to index",
+   "\
+This function takes a device name (eg. \"/dev/sdb\") and
+returns the index of the device in the list of devices.
+
+Index numbers start from 0.  The named device must exist,
+for example as a string returned from C<guestfs_list_devices>.
+
+See also C<guestfs_list_devices>, C<guestfs_part_to_dev>.");
+
 ]
 
 let all_functions = non_daemon_functions @ daemon_functions
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index 0ae9d1ef4..3d9988adc 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-334
+335