diff --git a/doc/geos.sgml b/doc/geos.sgml
index b550f770e..4dd15562f 100644
--- a/doc/geos.sgml
+++ b/doc/geos.sgml
@@ -833,7 +833,7 @@ but also removes it from drive RAM (not quite true, but it works like that). Aft
 <p>
 <tt/char ChangeDiskDevice (char newDevice)/
 <p>
-This function changes the logical number of the current device (in fact drives only) to the given one. It is
+This function changes the device number of the current device (in fact drives only) to the given one. It is
 usable for swapping drives. There's no check if the given <tt/newDevice/ already exist, so if you want
 to change the logical number of drive 8 to 9 and you already have a drive number 9 then GEOS will probably
 hang on disk access. Use safe, large numbers. Note that the safe IEC range is 8-30.