diff --git a/doc/README.Converters b/doc/README.Converters
index dfa22f0c4..c7946a83c 100644
--- a/doc/README.Converters
+++ b/doc/README.Converters
@@ -18,6 +18,13 @@ Please note, that when ever a command outputs anything to stderr,
 this will considered as a failure of the command. Most command line
 programs have a parameter (.e.g. `-q`) to suppress such an output.
 
+If you run php-fpm you may encounter problems with charsets based on
+UTF-8. Programms like `catdoc` read LANG from the environment to
+set the correct encoding of the output. php-fpm often clears the
+environment and programms like `catdoc` will not longer output any
+UTF-8 chars. In such a case you may want to set `clear_env=no` in
+php-fpm's configuration.
+
 Conversion to text for fulltext search
 =======================================