diff --git a/developer_manual/core/theming.rst b/developer_manual/core/theming.rst
index 2727b4110..ea77d38f7 100644
--- a/developer_manual/core/theming.rst
+++ b/developer_manual/core/theming.rst
@@ -86,7 +86,7 @@ Figure out the path of the old logo
 
 Replace the old picture, which position you found out as described under 1.3. by adding an extension in case you want to re-use it later.
 
-Creating an own logo
+Creating your own logo
 ^^^^^^^^^^^^^^^^^^^^
 
 If you want to do a quick exchange like (1) it's important to know the size of the picture before you start creating an own logo:
@@ -180,6 +180,22 @@ The other major color scheme is the blue header bar on the main navigation page
 This color we will change with the above as well.
 Save the file and refresh the browser for the changes to take effect.
 
+Changing file/folder type icons
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The core filetype icons are located in /core/img/filetypes/ directory.  
+Create a "filetypes" drrectory in your custom theme folder: 
+/themes/mytheme/core/img/filetypes/    
+
+Edit the filetype icon .svg files that you want to revise and place them in your new "filetypes" directory.
+
+Run this command from root of app:
+.. code-block:: php
+./occ maintenance:mimetype:update-js
+
+This will instruct app to use revised icons from your themes folder.
+
+
 
 How to change translations
 --------------------------