diff --git a/extra/project-euler/006/006.factor b/extra/project-euler/006/006.factor
index 3e2bf19f4a..2149353658 100644
--- a/extra/project-euler/006/006.factor
+++ b/extra/project-euler/006/006.factor
@@ -1,4 +1,4 @@
-! Copyright (c) 2007-2008 Aaron Schaefer.
+! Copyright (c) 2007, 2008 Aaron Schaefer.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: kernel math math.ranges sequences ;
 IN: project-euler.006
diff --git a/extra/project-euler/009/009.factor b/extra/project-euler/009/009.factor
index 2578808926..a1040d2bf2 100644
--- a/extra/project-euler/009/009.factor
+++ b/extra/project-euler/009/009.factor
@@ -1,4 +1,4 @@
-! Copyright (c) 2007-2008 Aaron Schaefer.
+! Copyright (c) 2007, 2008 Aaron Schaefer.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: kernel make math sequences sorting ;
 IN: project-euler.009
diff --git a/extra/project-euler/016/016.factor b/extra/project-euler/016/016.factor
index 80bbbbaec3..216fcb3523 100644
--- a/extra/project-euler/016/016.factor
+++ b/extra/project-euler/016/016.factor
@@ -1,4 +1,4 @@
-! Copyright (c) 2007-2008 Aaron Schaefer.
+! Copyright (c) 2007, 2008 Aaron Schaefer.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: math.functions project-euler.common sequences ;
 IN: project-euler.016
diff --git a/extra/project-euler/017/017.factor b/extra/project-euler/017/017.factor
index b47e2429f2..21e277da00 100644
--- a/extra/project-euler/017/017.factor
+++ b/extra/project-euler/017/017.factor
@@ -1,4 +1,4 @@
-! Copyright (c) 2007-2008 Aaron Schaefer.
+! Copyright (c) 2007, 2008 Aaron Schaefer.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: ascii kernel math.ranges math.text.english sequences ;
 IN: project-euler.017
diff --git a/extra/project-euler/020/020.factor b/extra/project-euler/020/020.factor
index 42d352858c..e75747b57c 100644
--- a/extra/project-euler/020/020.factor
+++ b/extra/project-euler/020/020.factor
@@ -1,4 +1,4 @@
-! Copyright (c) 2007-2008 Aaron Schaefer.
+! Copyright (c) 2007, 2008 Aaron Schaefer.
 ! See http://factorcode.org/license.txt for BSD license.
 USING: math.combinatorics project-euler.common sequences ;
 IN: project-euler.020
diff --git a/extra/project-euler/038/038.factor b/extra/project-euler/038/038.factor
index 78e3848a33..05bab5fc36 100755
--- a/extra/project-euler/038/038.factor
+++ b/extra/project-euler/038/038.factor
@@ -1,6 +1,7 @@
 ! Copyright (c) 2008 Aaron Schaefer.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: kernel math math.parser math.ranges project-euler.common sequences ;
+USING: kernel math math.parser math.ranges project-euler.common sequences
+    strings ;
 IN: project-euler.038
 
 ! http://projecteuler.net/index.php?section=problems&id=38
diff --git a/extra/project-euler/common/common.factor b/extra/project-euler/common/common.factor
index 5d1aa16a32..c609d82747 100644
--- a/extra/project-euler/common/common.factor
+++ b/extra/project-euler/common/common.factor
@@ -77,7 +77,7 @@ PRIVATE>
     number>string dup reverse = ;
 
 : pandigital? ( n -- ? )
-    number>string natural-sort "123456789" = ;
+    number>string natural-sort >string "123456789" = ;
 
 : pentagonal? ( n -- ? )
     dup 0 > [ 24 * 1+ sqrt 1+ 6 / 1 mod zero? ] [ drop f ] if ;