diff --git a/core/classes/tuple/tuple.factor b/core/classes/tuple/tuple.factor
index fb6f1ffba0..5ebcc7a286 100755
--- a/core/classes/tuple/tuple.factor
+++ b/core/classes/tuple/tuple.factor
@@ -102,7 +102,7 @@ ERROR: bad-superclass class ;
     dup tuple-predicate-quot define-predicate ;
 
 : superclass-size ( class -- n )
-    superclasses butlast-slice
+    superclasses but-last-slice
     [ slot-names length ] map sum ;
 
 : generate-tuple-slots ( class slots -- slot-specs )
diff --git a/core/inference/transforms/transforms.factor b/core/inference/transforms/transforms.factor
index cf3dcadd75..0040629edd 100755
--- a/core/inference/transforms/transforms.factor
+++ b/core/inference/transforms/transforms.factor
@@ -32,7 +32,7 @@ IN: inference.transforms
         drop [ no-case ]
     ] [
         dup peek quotation? [
-            dup peek swap butlast
+            dup peek swap but-last
         ] [
             [ no-case ] swap
         ] if case>quot
diff --git a/core/prettyprint/prettyprint-tests.factor b/core/prettyprint/prettyprint-tests.factor
index 834cad5b29..0faae398e9 100755
--- a/core/prettyprint/prettyprint-tests.factor
+++ b/core/prettyprint/prettyprint-tests.factor
@@ -114,7 +114,7 @@ unit-test
             [ parse-fresh drop ] with-compilation-unit
             [
                 "prettyprint.tests" lookup see
-            ] with-string-writer "\n" split butlast
+            ] with-string-writer "\n" split but-last
         ] keep =
     ] with-scope ;
 
diff --git a/core/prettyprint/sections/sections.factor b/core/prettyprint/sections/sections.factor
index 0ce8841256..7de5c2aee0 100644
--- a/core/prettyprint/sections/sections.factor
+++ b/core/prettyprint/sections/sections.factor
@@ -284,7 +284,7 @@ M: colon unindent-first-line? drop t ;
 
 ! Long section layout algorithm
 : chop-break ( seq -- seq )
-    dup peek line-break? [ butlast-slice chop-break ] when ;
+    dup peek line-break? [ but-last-slice chop-break ] when ;
 
 SYMBOL: prev
 SYMBOL: next
diff --git a/core/sequences/sequences-docs.factor b/core/sequences/sequences-docs.factor
index 67d26089b0..a2fcc3aea1 100755
--- a/core/sequences/sequences-docs.factor
+++ b/core/sequences/sequences-docs.factor
@@ -92,7 +92,7 @@ ARTICLE: "sequences-slices" "Subsequences and slices"
 { $subsection subseq }
 { $subsection head }
 { $subsection tail }
-{ $subsection butlast }
+{ $subsection but-last }
 { $subsection rest }
 { $subsection head* }
 { $subsection tail* }
@@ -107,7 +107,7 @@ ARTICLE: "sequences-slices" "Subsequences and slices"
 { $subsection <slice> }
 { $subsection head-slice }
 { $subsection tail-slice }
-{ $subsection butlast-slice }
+{ $subsection but-last-slice }
 { $subsection rest-slice }
 { $subsection head-slice* }
 { $subsection tail-slice* }
@@ -838,7 +838,7 @@ HELP: tail-slice
 { $description "Outputs a virtual sequence sharing storage with all elements from the " { $snippet "n" } "th index until the end of the input sequence." }
 { $errors "Throws an error if the index is out of bounds." } ;
 
-HELP: butlast-slice
+HELP: but-last-slice
 { $values { "seq" sequence } { "slice" "a slice" } }
 { $description "Outputs a virtual sequence sharing storage with all but the last element of the input sequence." }
 { $errors "Throws an error on an empty sequence." } ;
@@ -869,7 +869,7 @@ HELP: tail
 { $description "Outputs a new sequence consisting of the input sequence with the first n items removed." }
 { $errors "Throws an error if the index is out of bounds." } ;
 
-HELP: butlast
+HELP: but-last
 { $values { "seq" sequence } { "headseq" "a new sequence" } }
 { $description "Outputs a new sequence consisting of the input sequence with the last item removed." }
 { $errors "Throws an error on an empty sequence." } ;
diff --git a/core/sequences/sequences.factor b/core/sequences/sequences.factor
index 1e9d187c2d..8d0e3eec18 100755
--- a/core/sequences/sequences.factor
+++ b/core/sequences/sequences.factor
@@ -216,7 +216,7 @@ M: slice length dup slice-to swap slice-from - ;
 
 : tail-slice* ( seq n -- slice ) from-end tail-slice ;
 
-: butlast-slice ( seq -- slice ) 1 head-slice* ;
+: but-last-slice ( seq -- slice ) 1 head-slice* ;
 
 INSTANCE: slice virtual-sequence
 
@@ -265,7 +265,7 @@ PRIVATE>
 
 : tail* ( seq n -- tailseq ) from-end tail ;
 
-: butlast ( seq -- headseq ) 1 head* ;
+: but-last ( seq -- headseq ) 1 head* ;
 
 : copy ( src i dst -- )
     pick length >r 3dup check-copy spin 0 r>
@@ -675,13 +675,13 @@ PRIVATE>
     [ rest ] [ first ] bi ;
 
 : unclip-last ( seq -- butfirst last )
-    [ butlast ] [ peek ] bi ;
+    [ but-last ] [ peek ] bi ;
 
 : unclip-slice ( seq -- rest first )
     [ rest-slice ] [ first ] bi ;
 
 : unclip-last-slice ( seq -- butfirst last )
-    [ butlast-slice ] [ peek ] bi ;
+    [ but-last-slice ] [ peek ] bi ;
 
 : <flat-slice> ( seq -- slice )
     dup slice? [ { } like ] when 0 over length rot <slice> ;
diff --git a/core/splitting/splitting.factor b/core/splitting/splitting.factor
index be0652fd98..9f6ae75d32 100755
--- a/core/splitting/splitting.factor
+++ b/core/splitting/splitting.factor
@@ -104,7 +104,7 @@ M: sliced-clumps nth group@ <slice> ;
         1array
     ] [
         "\n" split [
-            butlast-slice [
+            but-last-slice [
                 "\r" ?tail drop "\r" split
             ] map
         ] keep peek "\r" split suffix concat
diff --git a/extra/help/lint/lint.factor b/extra/help/lint/lint.factor
index a120d791aa..a9ec7f9267 100755
--- a/extra/help/lint/lint.factor
+++ b/extra/help/lint/lint.factor
@@ -10,7 +10,7 @@ IN: help.lint
 
 : check-example ( element -- )
     rest [
-        butlast "\n" join 1vector
+        but-last "\n" join 1vector
         [
             use [ clone ] change
             [ eval>string ] with-datastack
diff --git a/extra/html/parser/analyzer/analyzer.factor b/extra/html/parser/analyzer/analyzer.factor
index 1912cfb65c..e9906f3f2a 100755
--- a/extra/html/parser/analyzer/analyzer.factor
+++ b/extra/html/parser/analyzer/analyzer.factor
@@ -99,7 +99,7 @@ IN: html.parser.analyzer
     
 : find-between ( i/f tag/f vector -- vector )
     find-between* dup length 3 >= [
-        [ rest-slice butlast-slice ] keep like
+        [ rest-slice but-last-slice ] keep like
     ] when ;
 
 : find-between-first ( string vector -- vector' )
diff --git a/extra/html/parser/utils/utils.factor b/extra/html/parser/utils/utils.factor
index c0eee57ead..5083b1cec2 100644
--- a/extra/html/parser/utils/utils.factor
+++ b/extra/html/parser/utils/utils.factor
@@ -36,7 +36,7 @@ IN: html.parser.utils
     dup quoted? [ quote ] unless ;
 
 : unquote ( str -- newstr )
-    dup quoted? [ butlast-slice rest-slice >string ] when ;
+    dup quoted? [ but-last-slice rest-slice >string ] when ;
 
 : quote? ( ch -- ? ) "'\"" member? ;
 
diff --git a/extra/inverse/inverse.factor b/extra/inverse/inverse.factor
index 8c19ade499..705c2d070b 100755
--- a/extra/inverse/inverse.factor
+++ b/extra/inverse/inverse.factor
@@ -197,7 +197,7 @@ DEFER: _
 
 \ prefix [ unclip ] define-inverse
 \ unclip [ prefix ] define-inverse
-\ suffix [ dup butlast swap peek ] define-inverse
+\ suffix [ dup but-last swap peek ] define-inverse
 
 ! Constructor inverse
 : deconstruct-pred ( class -- quot )
diff --git a/extra/koszul/koszul.factor b/extra/koszul/koszul.factor
index 5c337f8ce7..aecae1cf88 100755
--- a/extra/koszul/koszul.factor
+++ b/extra/koszul/koszul.factor
@@ -184,7 +184,7 @@ DEFER: (d)
     [ length ] keep [ (graded-ker/im-d) ] curry map ;
 
 : graded-betti ( generators -- seq )
-    basis graded graded-ker/im-d flip first2 butlast 0 prefix v- ;
+    basis graded graded-ker/im-d flip first2 but-last 0 prefix v- ;
 
 ! Bi-graded for two-step complexes
 : (bigraded-ker/im-d) ( u-deg z-deg bigraded-basis -- null/rank )
diff --git a/extra/locals/locals.factor b/extra/locals/locals.factor
index 4ad81ef00a..031348fbe8 100755
--- a/extra/locals/locals.factor
+++ b/extra/locals/locals.factor
@@ -101,7 +101,7 @@ UNION: special local quote local-word local-reader local-writer ;
     ] if ;
 
 : point-free-body ( quot args -- newquot )
-    >r butlast-slice r> [ localize ] curry map concat ;
+    >r but-last-slice r> [ localize ] curry map concat ;
 
 : point-free-end ( quot args -- newquot )
     over peek special?
diff --git a/extra/mortar/mortar.factor b/extra/mortar/mortar.factor
index 3d4d287ace..6173669ad0 100644
--- a/extra/mortar/mortar.factor
+++ b/extra/mortar/mortar.factor
@@ -122,7 +122,7 @@ over class-class-methods assoc-stack call ;
 ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
 : send-message-next ( object message -- )
-over object-class class-methods butlast assoc-stack call ;
+over object-class class-methods but-last assoc-stack call ;
 
 : <-~ scan parsed \ send-message-next parsed ; parsing
 
diff --git a/extra/multiline/multiline.factor b/extra/multiline/multiline.factor
index acff8c8669..ce79bdaf5f 100755
--- a/extra/multiline/multiline.factor
+++ b/extra/multiline/multiline.factor
@@ -14,7 +14,7 @@ IN: multiline
     ] [ ";" unexpected-eof ] if* ;
 
 : parse-here ( -- str )
-    [ (parse-here) ] "" make butlast
+    [ (parse-here) ] "" make but-last
     lexer get next-line ;
 
 : STRING:
@@ -34,7 +34,7 @@ IN: multiline
     [
         lexer get lexer-column swap (parse-multiline-string)
         lexer get set-lexer-column
-    ] "" make rest butlast ;
+    ] "" make rest but-last ;
 
 : <"
     "\">" parse-multiline-string parsed ; parsing
diff --git a/extra/porter-stemmer/porter-stemmer.factor b/extra/porter-stemmer/porter-stemmer.factor
index f6975ccce7..9a2a08bcbe 100644
--- a/extra/porter-stemmer/porter-stemmer.factor
+++ b/extra/porter-stemmer/porter-stemmer.factor
@@ -93,7 +93,7 @@ USING: kernel math parser sequences combinators splitting ;
         { [ "iz" ?tail ] [ "ize" append ] }
         {
             [ dup length 1- over double-consonant? ]
-            [ dup "lsz" last-is? [ butlast-slice ] unless ]
+            [ dup "lsz" last-is? [ but-last-slice ] unless ]
         }
         {
             [ t ]
@@ -120,7 +120,7 @@ USING: kernel math parser sequences combinators splitting ;
     } cond ;
 
 : step1c ( str -- newstr )
-    dup butlast-slice stem-vowel? [
+    dup but-last-slice stem-vowel? [
         "y" ?tail [ "i" append ] when
     ] when ;
 
@@ -196,18 +196,18 @@ USING: kernel math parser sequences combinators splitting ;
 : remove-e? ( str -- ? )
     dup consonant-seq dup 1 >
     [ 2drop t ]
-    [ 1 = [ butlast-slice cvc? not ] [ drop f ] if ] if ;
+    [ 1 = [ but-last-slice cvc? not ] [ drop f ] if ] if ;
 
 : remove-e ( str -- newstr )
     dup peek CHAR: e = [
-        dup remove-e? [ butlast-slice ] when
+        dup remove-e? [ but-last-slice ] when
     ] when ;
 
 : ll->l ( str -- newstr )
     {
         { [ dup peek CHAR: l = not ] [ ] }
         { [ dup length 1- over double-consonant? not ] [ ] }
-        { [ dup consonant-seq 1 > ] [ butlast-slice ] }
+        { [ dup consonant-seq 1 > ] [ but-last-slice ] }
         [ ]
     } cond ;
 
diff --git a/extra/project-euler/002/002.factor b/extra/project-euler/002/002.factor
index 6c9d331c90..108f5c1e94 100644
--- a/extra/project-euler/002/002.factor
+++ b/extra/project-euler/002/002.factor
@@ -41,7 +41,7 @@ PRIVATE>
 
 : fib-upto* ( n -- seq )
     0 1 [ pick over >= ] [ tuck + dup ] [ ] unfold 3nip
-    butlast-slice { 0 1 } prepend ;
+    but-last-slice { 0 1 } prepend ;
 
 : euler002a ( -- answer )
     1000000 fib-upto* [ even? ] filter sum ;
diff --git a/extra/project-euler/059/059.factor b/extra/project-euler/059/059.factor
index 25c086144f..dceb01bd16 100644
--- a/extra/project-euler/059/059.factor
+++ b/extra/project-euler/059/059.factor
@@ -78,7 +78,7 @@ INSTANCE: rollover immutable-sequence
     frequency-analysis sort-values keys peek ;
 
 : crack-key ( seq key-length -- key )
-    [ " " decrypt ] dip group butlast-slice
+    [ " " decrypt ] dip group but-last-slice
     flip [ most-frequent ] map ;
 
 PRIVATE>
diff --git a/extra/state-parser/state-parser-docs.factor b/extra/state-parser/state-parser-docs.factor
index cac0e30175..3027c01c19 100644
--- a/extra/state-parser/state-parser-docs.factor
+++ b/extra/state-parser/state-parser-docs.factor
@@ -69,4 +69,4 @@ HELP: next
 { $description "originally written as " { $code "spot inc" } ", code that would no longer run, this word moves the state of the XML parser to the next place in the source file, keeping track of appropriate debugging information." } ;
 
 HELP: parsing-error
-{ $class-description "class to which parsing errors delegate, containing information about which line and column the error occured on, and what the line was. Contains three slots, line, an integer, column, another integer, and line-str, a string" } ;
+{ $class-description "class from which parsing errors inherit, containing information about which line and column the error occured on, and what the line was. Contains three slots, line, an integer, column, another integer, and line-str, a string" } ;
diff --git a/extra/tools/deploy/backend/backend.factor b/extra/tools/deploy/backend/backend.factor
index 60d66e89cd..6dff511238 100755
--- a/extra/tools/deploy/backend/backend.factor
+++ b/extra/tools/deploy/backend/backend.factor
@@ -63,11 +63,11 @@ DEFER: ?make-staging-image
         dup empty? [
             "-i=" my-boot-image-name append ,
         ] [
-            dup butlast ?make-staging-image
+            dup but-last ?make-staging-image
 
             "-resource-path=" "" resource-path append ,
 
-            "-i=" over butlast staging-image-name append ,
+            "-i=" over but-last staging-image-name append ,
 
             "-run=tools.deploy.restage" ,
         ] if
diff --git a/extra/tuple-syntax/tuple-syntax.factor b/extra/tuple-syntax/tuple-syntax.factor
index 2b9b2c3fb4..cf439f6407 100755
--- a/extra/tuple-syntax/tuple-syntax.factor
+++ b/extra/tuple-syntax/tuple-syntax.factor
@@ -7,7 +7,7 @@ IN: tuple-syntax
 
 : parse-slot-writer ( tuple -- slot# )
     scan dup "}" = [ 2drop f ] [
-        butlast swap object-slots slot-named slot-spec-offset
+        but-last swap object-slots slot-named slot-spec-offset
     ] if ;
 
 : parse-slots ( accum tuple -- accum tuple )
diff --git a/extra/ui/gestures/gestures.factor b/extra/ui/gestures/gestures.factor
index d13e284160..9835e90b39 100755
--- a/extra/ui/gestures/gestures.factor
+++ b/extra/ui/gestures/gestures.factor
@@ -54,7 +54,7 @@ TUPLE: zoom-in-action ;  C: <zoom-in-action> zoom-in-action
 TUPLE: zoom-out-action ; C: <zoom-out-action> zoom-out-action
 
 : generalize-gesture ( gesture -- newgesture )
-    tuple>array butlast >tuple ;
+    tuple>array but-last >tuple ;
 
 ! Modifiers
 SYMBOLS: C+ A+ M+ S+ ;
diff --git a/extra/xml/errors/errors-tests.factor b/extra/xml/errors/errors-tests.factor
new file mode 100755
index 0000000000..402c76dc01
--- /dev/null
+++ b/extra/xml/errors/errors-tests.factor
@@ -0,0 +1,28 @@
+USING: continuations xml xml.errors tools.test kernel arrays xml.data state-parser quotations ;
+IN: xml.errors.tests
+
+: xml-error-test ( expected-error xml-string -- )
+    [ string>xml ] curry swap [ = ] curry must-fail-with ;
+
+T{ no-entity f 1 10 "nbsp" } "<x>&nbsp;</x>" xml-error-test
+T{ mismatched f 1 8 T{ name f "" "x" "" } T{ name f "" "y" "" }
+} "<x></y>" xml-error-test
+T{ unclosed f 1 4 V{ T{ name f "" "x" "" } } } "<x>" xml-error-test
+T{ nonexist-ns f 1 5 "x" } "<x:y/>" xml-error-test
+T{ unopened f 1 5 } "</x>" xml-error-test
+T{ not-yes/no f 1 41 "maybe" } "<?xml version='1.0' standalone='maybe'?><x/>" xml-error-test
+T{ extra-attrs f 1 32 V{ T{ name f "" "foo" f } }
+} "<?xml version='1.1' foo='bar'?><x/>" xml-error-test
+T{ bad-version f 1 28 "5 million" } "<?xml version='5 million'?><x/>" xml-error-test
+T{ notags f 1 0 } "" xml-error-test
+T{ multitags } "<x/><y/>" xml-error-test
+T{ bad-prolog  f 1 26 T{ prolog f "1.0" "UTF-8" f }
+} "<x/><?xml version='1.0'?>" xml-error-test
+T{ capitalized-prolog f 1 6 "XmL" } "<?XmL version='1.0'?><x/>"
+xml-error-test
+T{ pre/post-content f "x" t } "x<y/>" xml-error-test
+T{ versionless-prolog f 1 8 } "<?xml?><x/>" xml-error-test
+T{ bad-instruction f 1 11 T{ instruction f "xsl" }
+} "<x><?xsl?></x>" xml-error-test
+T{ bad-directive f 1 15 T{ directive f "DOCTYPE" }
+} "<x/><!DOCTYPE>" xml-error-test