diff --git a/extra/fuel/help/help.factor b/extra/fuel/help/help.factor
index 298124ffb4..ff7239ac8f 100644
--- a/extra/fuel/help/help.factor
+++ b/extra/fuel/help/help.factor
@@ -95,7 +95,7 @@ PRIVATE>
     [ [ see ] with-string-writer \ $code swap 2array ] bi 3array ; inline
 
 : (fuel-word-def) ( name -- str )
-    fuel-find-word [ [ def>> pprint ] with-string-writer ] when* ; inline
+    fuel-find-word [ [ def>> pprint ] with-string-writer ] [ f ] if* ; inline
 
 : (fuel-vocab-summary) ( name -- str ) >vocab-link summary ; inline
 
diff --git a/extra/inverse/inverse-docs.factor b/extra/inverse/inverse-docs.factor
index 8204f7174c..6b575d6d08 100644
--- a/extra/inverse/inverse-docs.factor
+++ b/extra/inverse/inverse-docs.factor
@@ -14,7 +14,17 @@ HELP: undo
 HELP: define-inverse
 { $values { "word" "a word" } { "quot" "the inverse" } }
 { $description "Defines the inverse of a given word, taking no arguments from the quotation, only the stack." }
-{ $see-also define-pop-inverse } ;
+{ $see-also define-dual define-involution define-pop-inverse } ;
+
+HELP: define-dual
+{ $values { "word1" "a word" } { "word2" "a word" } }
+{ $description "Defines the inverse of each word as being the other one." }
+{ $see-also define-inverse define-involution } ;
+
+HELP: define-involution
+{ $values { "word" "a word" } }
+{ $description "Defines a word as being its own inverse." }
+{ $see-also define-dual define-inverse } ;
 
 HELP: define-pop-inverse
 { $values { "word" "a word" } { "n" "number of arguments to be taken from the inverted quotation" } { "quot" "a quotation" } }
diff --git a/extra/inverse/inverse-tests.factor b/extra/inverse/inverse-tests.factor
index 5e662ed78f..a9234fcff4 100644
--- a/extra/inverse/inverse-tests.factor
+++ b/extra/inverse/inverse-tests.factor
@@ -75,3 +75,8 @@ C: <nil> nil
 [ { 3 } ] [ { 1 2 3 } [ { 1 2 } prepend ] undo ] unit-test
 [ { 1 2 3 } [ { 1 2 } append ] undo ] must-fail
 [ { 1 2 3 } [ { 2 3 } prepend ] undo ] must-fail
+
+[ [ sq ] ] [ [ sqrt ] [undo] ] unit-test
+[ [ sqrt ] ] [ [ sq ] [undo] ] unit-test
+[ [ not ] ] [ [ not ] [undo] ] unit-test
+[ { 3 2 1 } ] [ { 1 2 3 } [ reverse ] undo ] unit-test
diff --git a/extra/inverse/inverse.factor b/extra/inverse/inverse.factor
index a38af644b0..924a6d3814 100755
--- a/extra/inverse/inverse.factor
+++ b/extra/inverse/inverse.factor
@@ -20,6 +20,11 @@ M: fail summary drop "Matching failed" ;
 
 : define-inverse ( word quot -- ) "inverse" set-word-prop ;
 
+: define-dual ( word1 word2 -- )
+    2dup swap [ 1quotation define-inverse ] 2bi@ ;
+
+: define-involution ( word -- ) dup 1quotation define-inverse ;
+
 : define-math-inverse ( word quot1 quot2 -- )
     pick 1quotation 3array "math-inverse" set-word-prop ;
 
@@ -129,28 +134,24 @@ MACRO: undo ( quot -- ) [undo] ;
 
 ! Inverse of selected words
 
-\ swap [ swap ] define-inverse
+\ swap define-involution
 \ dup [ [ =/fail ] keep ] define-inverse
 \ 2dup [ over =/fail over =/fail ] define-inverse
 \ 3dup [ pick =/fail pick =/fail pick =/fail ] define-inverse
 \ pick [ [ pick ] dip =/fail ] define-inverse
 \ tuck [ swapd [ =/fail ] keep ] define-inverse
 
-\ not [ not ] define-inverse
+\ not define-involution
 \ >boolean [ { t f } memq? assure ] define-inverse
 
-\ tuple>array [ >tuple ] define-inverse
-\ >tuple [ tuple>array ] define-inverse
-\ reverse [ reverse ] define-inverse
+\ tuple>array \ >tuple define-dual
+\ reverse define-involution
 
 \ undo 1 [ [ call ] curry ] define-pop-inverse
 \ map 1 [ [undo] [ over sequence? assure map ] curry ] define-pop-inverse
 
-\ exp [ log ] define-inverse
-\ log [ exp ] define-inverse
-\ not [ not ] define-inverse
-\ sq [ sqrt ] define-inverse
-\ sqrt [ sq ] define-inverse
+\ exp \ log define-dual
+\ sq \ sqrt define-dual
 
 ERROR: missing-literal ;
 
@@ -204,8 +205,7 @@ DEFER: _
 \ first3 [ 3array ] define-inverse
 \ first4 [ 4array ] define-inverse
 
-\ prefix [ unclip ] define-inverse
-\ unclip [ prefix ] define-inverse
+\ prefix \ unclip define-dual
 \ suffix [ dup but-last swap peek ] define-inverse
 
 \ append 1 [ [ ?tail assure ] curry ] define-pop-inverse
diff --git a/misc/fuel/fuel-syntax.el b/misc/fuel/fuel-syntax.el
index 7f0fa313c2..b74b0afc11 100644
--- a/misc/fuel/fuel-syntax.el
+++ b/misc/fuel/fuel-syntax.el
@@ -94,7 +94,7 @@
   "\\_<-?[0-9]+\\.[0-9]*\\([eE][+-]?[0-9]+\\)?\\_>")
 
 (defconst fuel-syntax--bad-string-regex
-  "\"[^\"]*$")
+  "\"\\([^\"]\\|\\\\\"\\)*\n")
 
 (defconst fuel-syntax--word-definition-regex
   (fuel-syntax--second-word-regex
@@ -226,7 +226,7 @@
     ;; CHARs:
     ("CHAR: \\(.\\)\\( \\|$\\)" (1 "w"))
     ;; Strings
-    ("\\(\"\\)[^\n\r\f]*\\(\"\\)" (1 "\"") (2 "\""))
+    ("\\(\"\\)\\([^\n\r\f\\\"]\\|\\\\\"?\\)*\\(\"\\)" (1 "\"") (3 "\""))
     ;; Let and lambda:
     ("\\_<\\(!(\\) .* \\()\\)" (1 "<") (2 ">"))
     ("\\(\\[\\)\\(let\\|wlet\\|let\\*\\)\\( \\|$\\)" (1 "(]"))