diff --git a/basis/bit-arrays/bit-arrays-tests.factor b/basis/bit-arrays/bit-arrays-tests.factor
index 24c27fa15b..1de49d353d 100644
--- a/basis/bit-arrays/bit-arrays-tests.factor
+++ b/basis/bit-arrays/bit-arrays-tests.factor
@@ -78,3 +78,5 @@ IN: bit-arrays.tests
 } bit-array>integer ] unit-test
 
 [ 49 ] [ 49 <bit-array> dup set-bits [ ] count ] unit-test
+
+[ HEX: 100 ] [ ?{ f f f f f f f f t } bit-array>integer ] unit-test
diff --git a/basis/bit-arrays/bit-arrays.factor b/basis/bit-arrays/bit-arrays.factor
index 18796fbfed..f1ba71ce1e 100644
--- a/basis/bit-arrays/bit-arrays.factor
+++ b/basis/bit-arrays/bit-arrays.factor
@@ -83,7 +83,7 @@ M: bit-array byte-length length 7 + -3 shift ;
     ] if ;
 
 : bit-array>integer ( bit-array -- n )
-    0 swap underlying>> dup length [
+    0 swap underlying>> dup length <reversed> [
         alien-unsigned-1 swap 8 shift bitor
     ] with each ;
 
diff --git a/extra/math/primes/authors.txt b/basis/math/primes/authors.txt
similarity index 100%
rename from extra/math/primes/authors.txt
rename to basis/math/primes/authors.txt
diff --git a/extra/math/primes/erato/authors.txt b/basis/math/primes/erato/authors.txt
similarity index 100%
rename from extra/math/primes/erato/authors.txt
rename to basis/math/primes/erato/authors.txt
diff --git a/extra/math/primes/erato/erato-docs.factor b/basis/math/primes/erato/erato-docs.factor
similarity index 100%
rename from extra/math/primes/erato/erato-docs.factor
rename to basis/math/primes/erato/erato-docs.factor
diff --git a/extra/math/primes/erato/erato-tests.factor b/basis/math/primes/erato/erato-tests.factor
similarity index 100%
rename from extra/math/primes/erato/erato-tests.factor
rename to basis/math/primes/erato/erato-tests.factor
diff --git a/extra/math/primes/erato/erato.factor b/basis/math/primes/erato/erato.factor
similarity index 100%
rename from extra/math/primes/erato/erato.factor
rename to basis/math/primes/erato/erato.factor
diff --git a/extra/math/primes/erato/summary.txt b/basis/math/primes/erato/summary.txt
similarity index 100%
rename from extra/math/primes/erato/summary.txt
rename to basis/math/primes/erato/summary.txt
diff --git a/extra/math/primes/factors/authors.txt b/basis/math/primes/factors/authors.txt
similarity index 100%
rename from extra/math/primes/factors/authors.txt
rename to basis/math/primes/factors/authors.txt
diff --git a/extra/math/primes/factors/factors-docs.factor b/basis/math/primes/factors/factors-docs.factor
similarity index 100%
rename from extra/math/primes/factors/factors-docs.factor
rename to basis/math/primes/factors/factors-docs.factor
diff --git a/extra/math/primes/factors/factors-tests.factor b/basis/math/primes/factors/factors-tests.factor
similarity index 100%
rename from extra/math/primes/factors/factors-tests.factor
rename to basis/math/primes/factors/factors-tests.factor
diff --git a/basis/math/primes/factors/factors.factor b/basis/math/primes/factors/factors.factor
new file mode 100644
index 0000000000..05d6b26010
--- /dev/null
+++ b/basis/math/primes/factors/factors.factor
@@ -0,0 +1,29 @@
+! Copyright (C) 2007-2009 Samuel Tardieu.
+! See http://factorcode.org/license.txt for BSD license.
+USING: arrays combinators kernel make math math.primes sequences ;
+IN: math.primes.factors
+
+<PRIVATE
+
+: count-factor ( n d -- n' c )
+    [ 1 ] 2dip [ /i ] keep
+    [ dupd /mod zero? ] curry [ nip [ 1+ ] dip ] [ drop ] while
+    swap ;
+
+: write-factor ( n d -- n' d )
+    2dup mod zero? [ [ [ count-factor ] keep swap 2array , ] keep ] when ;
+
+PRIVATE>
+
+: group-factors ( n -- seq )
+    [ 2 [ over 1 > ] [ write-factor next-prime ] [ ] while 2drop ] { } make ;
+
+: unique-factors ( n -- seq ) group-factors [ first ] map ;
+
+: factors ( n -- seq ) group-factors [ first2 swap <array> ] map concat ;
+
+: totient ( n -- t )
+    {
+        { [ dup 2 < ] [ drop 0 ] }
+        [ dup unique-factors [ 1 [ 1- * ] reduce ] [ product ] bi / * ]
+    } cond ; foldable
diff --git a/extra/math/primes/factors/summary.txt b/basis/math/primes/factors/summary.txt
similarity index 100%
rename from extra/math/primes/factors/summary.txt
rename to basis/math/primes/factors/summary.txt
diff --git a/extra/math/primes/primes-docs.factor b/basis/math/primes/primes-docs.factor
similarity index 67%
rename from extra/math/primes/primes-docs.factor
rename to basis/math/primes/primes-docs.factor
index 516b081624..c7dbc950e8 100644
--- a/extra/math/primes/primes-docs.factor
+++ b/basis/math/primes/primes-docs.factor
@@ -11,15 +11,7 @@ HELP: prime?
 { $values { "n" "an integer" } { "?" "a boolean" } }
 { $description "Test if an integer is a prime number." } ;
 
-{ lprimes lprimes-from primes-upto primes-between } related-words
-
-HELP: lprimes
-{ $values { "list" "a lazy list" } }
-{ $description "Return a sorted list containing all the prime numbers." } ;
-
-HELP: lprimes-from
-{ $values { "n" "an integer" } { "list" "a lazy list" } }
-{ $description "Return a sorted list containing all the prime numbers greater or equal to " { $snippet "n" } "." } ;
+{ primes-upto primes-between } related-words
 
 HELP: primes-upto
 { $values { "n" "an integer" } { "seq" "a sequence" } }
diff --git a/basis/math/primes/primes-tests.factor b/basis/math/primes/primes-tests.factor
new file mode 100644
index 0000000000..db738399ef
--- /dev/null
+++ b/basis/math/primes/primes-tests.factor
@@ -0,0 +1,9 @@
+USING: arrays math.primes tools.test ;
+
+{ 1237 } [ 1234 next-prime ] unit-test
+{ f t } [ 1234 prime? 1237 prime? ] unit-test
+{ { 2 3 5 7 } } [ 10 primes-upto >array ] unit-test
+{ { 999983 1000003 } } [ 999982 1000010 primes-between >array ] unit-test
+
+{ { 4999963 4999999 5000011 5000077 5000081 } }
+[ 4999962 5000082 primes-between >array ] unit-test
diff --git a/extra/math/primes/primes.factor b/basis/math/primes/primes.factor
similarity index 69%
rename from extra/math/primes/primes.factor
rename to basis/math/primes/primes.factor
index fa42d7385a..807ebf097b 100644
--- a/extra/math/primes/primes.factor
+++ b/basis/math/primes/primes.factor
@@ -1,7 +1,7 @@
-! Copyright (C) 2007 Samuel Tardieu.
+! Copyright (C) 2007-2009 Samuel Tardieu.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: combinators kernel lists.lazy math math.functions
-math.miller-rabin math.order math.primes.erato math.ranges sequences ;
+USING: combinators kernel math math.functions math.miller-rabin
+math.order math.primes.erato math.ranges sequences ;
 IN: math.primes
 
 <PRIVATE
@@ -23,11 +23,6 @@ PRIVATE>
 : next-prime ( n -- p )
     next-odd [ dup really-prime? ] [ 2 + ] [ ] until ; foldable
 
-: lprimes ( -- list ) 2 [ next-prime ] lfrom-by ;
-
-: lprimes-from ( n -- list )
-    dup 3 < [ drop lprimes ] [ 1- next-prime [ next-prime ] lfrom-by ] if ;
-
 : primes-between ( low high -- seq )
     [ dup 3 max dup even? [ 1 + ] when ] dip
     2 <range> [ prime? ] filter
diff --git a/extra/math/primes/summary.txt b/basis/math/primes/summary.txt
similarity index 100%
rename from extra/math/primes/summary.txt
rename to basis/math/primes/summary.txt
diff --git a/extra/math/primes/factors/factors.factor b/extra/math/primes/factors/factors.factor
deleted file mode 100644
index 282c46c82e..0000000000
--- a/extra/math/primes/factors/factors.factor
+++ /dev/null
@@ -1,40 +0,0 @@
-! Copyright (C) 2007-2009 Samuel Tardieu.
-! See http://factorcode.org/license.txt for BSD license.
-USING: arrays kernel lists make math math.primes sequences ;
-IN: math.primes.factors
-
-<PRIVATE
-
-: count-factor ( n d -- n' c )
-    0 [ [ 2dup mod zero? ] dip swap ] [ [ [ / ] keep ] dip 1+ ] [ ] while nip ;
-
-: (factor) ( n d -- n' ) dup [ , ] curry [ count-factor ] dip times ;
-
-: (count) ( n d -- n' )
-    dup [ swap 2array , ] curry
-    [ count-factor dup zero? [ drop ] ] dip if ;
-
-: (unique) ( n d -- n' )
-    dup [ , ] curry [ count-factor zero? ] dip unless ;
-
-: (factors) ( quot list n -- )
-    dup 1 > [
-        swap uncons swap [ pick call ] dip swap (factors)
-    ] [ 3drop ] if ; inline recursive
-
-: decompose ( n quot -- seq ) [ lprimes rot (factors) ] { } make ; inline
-
-PRIVATE>
-
-: factors ( n -- seq ) [ (factor) ] decompose ; flushable
-
-: group-factors ( n -- seq ) [ (count) ] decompose ; flushable
-
-: unique-factors ( n -- seq ) [ (unique) ] decompose ; flushable
-
-: totient ( n -- t )
-    dup 2 < [
-        drop 0
-    ] [
-        dup unique-factors [ 1 [ 1- * ] reduce ] [ product ] bi / *
-    ] if ; foldable
diff --git a/extra/math/primes/lists/authors.txt b/extra/math/primes/lists/authors.txt
new file mode 100644
index 0000000000..f3b0233f74
--- /dev/null
+++ b/extra/math/primes/lists/authors.txt
@@ -0,0 +1 @@
+Samuel Tardieu
diff --git a/extra/math/primes/lists/lists-docs.factor b/extra/math/primes/lists/lists-docs.factor
new file mode 100644
index 0000000000..ecab12ceb7
--- /dev/null
+++ b/extra/math/primes/lists/lists-docs.factor
@@ -0,0 +1,10 @@
+USING: help.markup help.syntax ;
+IN: math.primes.lists
+
+HELP: lprimes
+{ $values { "list" "a lazy list" } }
+{ $description "Return a sorted list containing all the prime numbers." } ;
+
+HELP: lprimes-from
+{ $values { "n" "an integer" } { "list" "a lazy list" } }
+{ $description "Return a sorted list containing all the prime numbers greater or equal to " { $snippet "n" } "." } ;
diff --git a/extra/math/primes/lists/lists-tests.factor b/extra/math/primes/lists/lists-tests.factor
new file mode 100644
index 0000000000..3bd7d70365
--- /dev/null
+++ b/extra/math/primes/lists/lists-tests.factor
@@ -0,0 +1,6 @@
+USING: lists.lazy math.primes.lists tools.test ;
+
+{ { 2 3 5 7 11 13 17 19 23 29 } } [ 10 lprimes ltake list>array ] unit-test
+{ { 101 103 107 109 113 } } [ 5 100 lprimes-from ltake list>array ] unit-test
+{ { 1000117 1000121 } } [ 2 1000100 lprimes-from ltake list>array ] unit-test
+{ { 999983 1000003 } } [ 2 999982 lprimes-from ltake list>array ] unit-test
diff --git a/extra/math/primes/lists/lists.factor b/extra/math/primes/lists/lists.factor
new file mode 100644
index 0000000000..13f314f6ba
--- /dev/null
+++ b/extra/math/primes/lists/lists.factor
@@ -0,0 +1,9 @@
+! Copyright (C) 2007-2009 Samuel Tardieu.
+! See http://factorcode.org/license.txt for BSD license.
+USING: kernel lists.lazy math math.primes ;
+IN: math.primes.lists
+
+: lprimes ( -- list ) 2 [ next-prime ] lfrom-by ;
+
+: lprimes-from ( n -- list )
+    dup 3 < [ drop lprimes ] [ 1- next-prime [ next-prime ] lfrom-by ] if ;
diff --git a/extra/math/primes/lists/summary.txt b/extra/math/primes/lists/summary.txt
new file mode 100644
index 0000000000..39a780a26b
--- /dev/null
+++ b/extra/math/primes/lists/summary.txt
@@ -0,0 +1 @@
+Infinite stream of prime numbers through lazy lists
diff --git a/extra/math/primes/primes-tests.factor b/extra/math/primes/primes-tests.factor
deleted file mode 100644
index b0b25285c0..0000000000
--- a/extra/math/primes/primes-tests.factor
+++ /dev/null
@@ -1,14 +0,0 @@
-USING: arrays math.primes tools.test lists.lazy ;
-
-{ 1237 } [ 1234 next-prime ] unit-test
-{ f t } [ 1234 prime? 1237 prime? ] unit-test
-{ { 2 3 5 7 11 13 17 19 23 29 } } [ 10 lprimes ltake list>array ] unit-test
-{ { 101 103 107 109 113 } } [ 5 100 lprimes-from ltake list>array ] unit-test
-{ { 1000117 1000121 } } [ 2 1000100 lprimes-from ltake list>array ] unit-test
-{ { 999983 1000003 } } [ 2 999982 lprimes-from ltake list>array ] unit-test
-{ { 2 3 5 7 } } [ 10 primes-upto >array ] unit-test
-{ { 999983 1000003 } } [ 999982 1000010 primes-between >array ] unit-test
-
-{ { 4999963 4999999 5000011 5000077 5000081 } }
-[ 4999962 5000082 primes-between >array ]
-unit-test
diff --git a/extra/project-euler/007/007.factor b/extra/project-euler/007/007.factor
index f2b659fe94..f40108e4d7 100644
--- a/extra/project-euler/007/007.factor
+++ b/extra/project-euler/007/007.factor
@@ -1,6 +1,6 @@
 ! Copyright (c) 2007 Aaron Schaefer.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: lists math math.primes ;
+USING: lists math math.primes.lists ;
 IN: project-euler.007
 
 ! http://projecteuler.net/index.php?section=problems&id=7
diff --git a/extra/project-euler/134/134.factor b/extra/project-euler/134/134.factor
index 7bdf17ef68..e00e86865d 100644
--- a/extra/project-euler/134/134.factor
+++ b/extra/project-euler/134/134.factor
@@ -1,7 +1,7 @@
 ! Copyright (c) 2007 Samuel Tardieu.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: arrays kernel lists lists.lazy math.algebra math math.functions
-    math.order math.primes math.ranges project-euler.common sequences ;
+    math.order math.primes.lists math.ranges project-euler.common sequences ;
 IN: project-euler.134
 
 ! http://projecteuler.net/index.php?section=problems&id=134