--- a/src/code/extfmts.lisp
+++ b/src/code/extfmts.lisp
@@ -1133,9 +1133,12 @@ character and illegal outputs are replaced by a question mark.")
   The standard streams are sys::*stdin*, sys::*stdout*, and
   sys::*stderr*, which are normally the input and/or output streams
   for *standard-input* and *standard-output*.  Also sets sys::*tty*
-  (normally *terminal-io* to the given external format.  If the
-  optional argument Filenames is gvien, then the filename encoding is
-  set to the specified format."
+  (normally *terminal-io* to the given external format.  The value of
+  *default-external-format* is not changed.
+
+  If the optional argument Filenames is given, then the filename
+  encoding is set to the specified format, if it has not already been
+  specified previously."
   (unless (find-external-format terminal)
     (error (intl:gettext "Can't find external-format ~S.") terminal))
   (setf (stream-external-format sys:*stdin*) terminal

--- a/src/i18n/locale/cmucl.pot
+++ b/src/i18n/locale/cmucl.pot
@@ -4729,7 +4729,7 @@ msgstr ""
 
 #: src/code/float-trap.lisp
 msgid ""
-"Sets floating-point modes according to the give options and the\n"
+"Encode the floating-point modes according to the give options and the\n"
 "  specified mode, Floating-Point-Modes.  The resulting new mode is\n"
 "  returned.  If a keyword is not supplied, then the current value is\n"
 "  preserved.  Possible keywords:\n"