diff --git a/basis/io/unix/files/files-docs.factor b/basis/io/unix/files/files-docs.factor
index 7b4ce10b86..5b5e257c5e 100644
--- a/basis/io/unix/files/files-docs.factor
+++ b/basis/io/unix/files/files-docs.factor
@@ -28,7 +28,7 @@ HELP: file-username
      { "string" string } }
 { $description "Returns the username for a given file." } ;
 
-HELP: file-username-id
+HELP: file-user-id
 { $values
      { "path" "a pathname string" }
      { "uid" integer } }
@@ -107,15 +107,15 @@ HELP: set-file-times
      { "path" "a pathname string" } { "timestamps" "an array of two timestamps" } }
 { $description "Sets the access and write timestamps for a file as provided in the input array. A value of " { $link f } " provided for either of the timestamps will not change that timestamp." } ;
 
-HELP: set-file-username
+HELP: set-file-user
 { $values
      { "path" "a pathname string" } { "string/id" "a string or a user id" } }
 { $description "Sets a file's user id from the given user id or username." } ;
 
-HELP: set-file-write-time
+HELP: set-file-modified-time
 { $values
      { "path" "a pathname string" } { "timestamp" timestamp } }
-{ $description "Sets a file's last write timestamp." } ;
+{ $description "Sets a file's last modified timestamp, or write timestamp." } ;
 
 HELP: set-gid
 { $values
@@ -251,16 +251,16 @@ ARTICLE: "unix-file-timestamps" "Unix file timestamps"
 { $subsection set-file-times }
 "Setting just the last access time:"
 { $subsection set-file-access-time }
-"Setting just the last write time:"
-{ $subsection set-file-write-time } ;
+"Setting just the last modified time:"
+{ $subsection set-file-modified-time } ;
 
 
 ARTICLE: "unix-file-ids" "Unix file user and group ids"
 "Reading file user data:"
-{ $subsection file-username-id }
+{ $subsection file-user-id }
 { $subsection file-username }
 "Setting file user data:"
-{ $subsection set-file-username }
+{ $subsection set-file-user }
 "Reading file group data:"
 { $subsection file-group-id }
 { $subsection file-group-name }
diff --git a/basis/io/unix/files/files-tests.factor b/basis/io/unix/files/files-tests.factor
index 040b191d27..28c25c0964 100644
--- a/basis/io/unix/files/files-tests.factor
+++ b/basis/io/unix/files/files-tests.factor
@@ -1,4 +1,6 @@
-USING: tools.test io.files ;
+USING: tools.test io.files continuations kernel io.unix.files
+math.bitwise calendar accessors math.functions math unix.users
+unix.groups arrays sequences ;
 IN: io.unix.files.tests
 
 [ "/usr/libexec/" ] [ "/usr/libexec/awk/" parent-directory ] unit-test
@@ -27,3 +29,109 @@ IN: io.unix.files.tests
 [ "/lib/bux" ] [ "/usr" "/lib/bux" append-path ] unit-test
 [ "/lib/bux/" ] [ "/usr" "/lib/bux/" append-path ] unit-test
 [ t ] [ "/foo" absolute-path? ] unit-test
+
+: test-file ( -- path )
+    "permissions" temp-file ;
+
+: prepare-test-file ( -- )
+    [ test-file delete-file ] ignore-errors
+    test-file touch-file ;
+
+: perms ( -- n )
+    test-file file-permissions OCT: 7777 mask ;
+
+prepare-test-file
+
+[ t ]
+[ test-file { USER-ALL GROUP-ALL OTHER-ALL } flags set-file-permissions perms OCT: 777 = ] unit-test
+
+[ t ] [ test-file user-read? ] unit-test
+[ t ] [ test-file user-write? ] unit-test
+[ t ] [ test-file user-execute? ] unit-test
+[ t ] [ test-file group-read? ] unit-test
+[ t ] [ test-file group-write? ] unit-test
+[ t ] [ test-file group-execute? ] unit-test
+[ t ] [ test-file other-read? ] unit-test
+[ t ] [ test-file other-write? ] unit-test
+[ t ] [ test-file other-execute? ] unit-test
+
+[ t ]
+[ test-file f set-other-execute perms OCT: 776 = ] unit-test
+
+[ t ]
+[ test-file f set-other-write perms OCT: 774 = ] unit-test
+
+[ t ]
+[ test-file f set-other-read perms OCT: 770 = ] unit-test
+
+[ t ]
+[ test-file f set-group-execute perms OCT: 760 = ] unit-test
+
+[ t ]
+[ test-file f set-group-write perms OCT: 740 = ] unit-test
+
+[ t ]
+[ test-file f set-group-read perms OCT: 700 = ] unit-test
+
+[ t ]
+[ test-file f set-user-execute perms OCT: 600 = ] unit-test
+
+[ t ]
+[ test-file f set-user-write perms OCT: 400 = ] unit-test
+
+[ t ]
+[ test-file f set-user-read perms OCT: 000 = ] unit-test
+
+[ t ]
+[ test-file { USER-ALL GROUP-ALL OTHER-EXECUTE } flags set-file-permissions perms OCT: 771 = ] unit-test
+
+prepare-test-file
+
+[ t ]
+[
+    test-file now
+    [ set-file-access-time ] 2keep
+    [ file-info accessed>> ]
+    [ [ truncate >integer ] change-second ] bi* =
+] unit-test
+
+[ t ]
+[
+    test-file now
+    [ set-file-modified-time ] 2keep
+    [ file-info modified>> ]
+    [ [ truncate >integer ] change-second ] bi* =
+] unit-test
+
+[ t ]
+[
+    test-file now [ dup 2array set-file-times ] 2keep
+    [ file-info [ modified>> ] [ accessed>> ] bi ] dip
+    3array
+    [ [ truncate >integer ] change-second ] map all-equal?
+] unit-test
+
+[ ] [ test-file f now 2array set-file-times ] unit-test
+[ ] [ test-file now f 2array set-file-times ] unit-test
+[ ] [ test-file f f 2array set-file-times ] unit-test
+
+
+[ ] [ test-file real-username set-file-user ] unit-test
+[ ] [ test-file real-user-id set-file-user ] unit-test
+[ ] [ test-file real-group-name set-file-group ] unit-test
+[ ] [ test-file real-group-id set-file-group ] unit-test
+
+[ t ] [ test-file file-username real-username = ] unit-test
+[ t ] [ test-file file-group-name real-group-name = ] unit-test
+
+[ ]
+[ test-file real-user-id real-group-id set-file-ids ] unit-test
+
+[ ]
+[ test-file f real-group-id set-file-ids ] unit-test
+
+[ ]
+[ test-file real-user-id f set-file-ids ] unit-test
+
+[ ]
+[ test-file f f set-file-ids ] unit-test
diff --git a/basis/io/unix/files/files.factor b/basis/io/unix/files/files.factor
index 49510f9841..40ef9ad859 100644
--- a/basis/io/unix/files/files.factor
+++ b/basis/io/unix/files/files.factor
@@ -144,7 +144,7 @@ os {
     
 : chmod-set-bit ( path mask ? -- ) 
     [ dup stat-mode ] 2dip 
-    [ set-bit ] [ clear-bit ] if chmod io-error ;
+    [ bitor ] [ unmask ] if chmod io-error ;
 
 : file-mode? ( path mask -- ? ) [ stat-mode ] dip mask? ;
 
@@ -220,22 +220,22 @@ PRIVATE>
 : set-file-access-time ( path timestamp -- )
     f 2array set-file-times ;
 
-: set-file-write-time ( path timestamp -- )
+: set-file-modified-time ( path timestamp -- )
     f swap 2array set-file-times ;
 
 : set-file-ids ( path uid gid -- )
     [ normalize-path ] 2dip
     [ [ -1 ] unless* ] bi@ chown io-error ;
 
-GENERIC: set-file-username ( path string/id -- )
+GENERIC: set-file-user ( path string/id -- )
 
 GENERIC: set-file-group ( path string/id -- )
 
-M: integer set-file-username ( path uid -- )
+M: integer set-file-user ( path uid -- )
     f set-file-ids ;
 
-M: string set-file-username ( path string -- )
-    username-id f set-file-ids ;
+M: string set-file-user ( path string -- )
+    user-id f set-file-ids ;
     
 M: integer set-file-group ( path gid -- )
     f swap set-file-ids ;
@@ -244,11 +244,11 @@ M: string set-file-group ( path string -- )
     group-id
     f swap set-file-ids ;
 
-: file-username-id ( path -- uid )
+: file-user-id ( path -- uid )
     normalize-path file-info uid>> ;
 
 : file-username ( path -- string )
-    file-username-id username ;
+    file-user-id username ;
 
 : file-group-id ( path -- gid )
     normalize-path file-info gid>> ;