diff --git a/src/code/filesys.lisp b/src/code/filesys.lisp
index ab2f564b81b6ba9cd39e908e95846f03551cf97d..308b8b542c191703b32d1f57ef7ff2a0f98ed431 100644
--- a/src/code/filesys.lisp
+++ b/src/code/filesys.lisp
@@ -488,7 +488,14 @@
 	   (error (intl:gettext ":BACK cannot be represented in namestrings.")))
 	  ((member :wild-inferiors)
 	   (pieces "**/"))
-	  ((or simple-string pattern (eql :wild))
+	  (simple-string
+	   (when (zerop (length dir))
+	     (error (intl:gettext "Cannot represent \"\" in namestrings.")))
+	   (when (string-equal dir "/")
+	     (error (intl:gettext "Cannot represent an explicit directory separator in namestrings.")))
+	   (pieces (unparse-unix-piece dir))
+	   (pieces "/"))
+	  ((or pattern (eql :wild))
 	   (pieces (unparse-unix-piece dir))
 	   (pieces "/"))
 	  (t
diff --git a/src/i18n/locale/cmucl.pot b/src/i18n/locale/cmucl.pot
index 92ace3df87aacd73e9b013f6f0d96490bb138e1f..a1087ca865431206817db05d5c30798e72a49e3b 100644
--- a/src/i18n/locale/cmucl.pot
+++ b/src/i18n/locale/cmucl.pot
@@ -9026,7 +9026,15 @@ msgid ""
 "Convert String to octets using the specified External-format.  The\n"
 "  string is bounded by Start (defaulting to 0) and End (defaulting to\n"
 "  the end of the string.  If Buffer is given, the octets are stored\n"
-"  there.  If not, a new buffer is created."
+"  there.  If not, a new buffer is created.  Buffer-start specifies\n"
+"  where in the buffer the first octet will be placed.\n"
+"\n"
+"  Three values are returned: The buffer, the number of valid octets\n"
+"  written, and the number of characters converted.  Note that the\n"
+"  actual number of octets written may be greater than the returned\n"
+"  value, These represent the partial octets of the next character to\n"
+"  be converted, but there was not enough room to hold the complete set\n"
+"  of octets."
 msgstr ""
 
 #: src/code/extfmts.lisp
@@ -9806,6 +9814,14 @@ msgstr ""
 msgid ":BACK cannot be represented in namestrings."
 msgstr ""
 
+#: src/code/filesys.lisp
+msgid "Cannot represent \"\" in namestrings."
+msgstr ""
+
+#: src/code/filesys.lisp
+msgid "Cannot represent an explicit directory separator in namestrings."
+msgstr ""
+
 #: src/code/filesys.lisp
 msgid "Cannot specify a directory separator in a pathname name: ~S"
 msgstr ""