diff --git a/manifest b/manifest
index c2d1ebd93c..5f6149e43c 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Make\ssure\sthe\sstrftime()\sdate\sconversions\sput\sin\sleading\szeros\scorrectly.\nTicket\s#2276.\s(CVS\s3749)
-D 2007-03-29T17:57:21
+C Change\sthe\sname\sof\sPAGER_SECTOR_SIZE\sto\sSQLITE_DEFAULT_SECTOR_SIZE.\s\sMake\nthe\snew\sOS-layer\sinterface\sroutine\sfor\sfinding\ssector\ssize\soptional.\s(CVS\s3750)
+D 2007-03-29T18:19:52
 F Makefile.in 2f2c3bf69faf0ae7b8e8af4f94f1986849034530
 F Makefile.linux-gcc 2d8574d1ba75f129aba2019f0b959db380a90935
 F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
@@ -75,18 +75,18 @@ F src/legacy.c 2631df6a861f830d6b1c0fe92b9fdd745b2c0cd6
 F src/loadext.c c186ad5c9e8a0aaa73d0caf5f604d112e45e8b89
 F src/main.c 3ca92e8f2397da413c39f5a102e5675f5c5fa78a
 F src/md5.c c5fdfa5c2593eaee2e32a5ce6c6927c986eaf217
-F src/os.c 6df3e9c23eaa982d3e66ef770ad2519de5dd4d97
-F src/os.h ec780b3561d0bb887d13f193a1a889872c44a236
+F src/os.c 5a194b9b9a10dc66543d4ca22bc0db40c5cc5ef1
+F src/os.h 506acdfd0a63802434ceacdbfd7c006e5d90fc53
 F src/os_common.h c86e8cbd6150ca06d46b09ec02ff5fc5d4b05285
-F src/os_os2.c cb2c4f6d28810b5cee682d8df92352464d5c9d95
+F src/os_os2.c 313ece302183dfd83c4f281e1972656b7e6b672e
 F src/os_os2.h e5f17dd69333632bbc3112881ea407c37d245eb3
 F src/os_test.c 49833426101f99aee4bb5f6a44b7c4b2029fda1c
 F src/os_test.h 903c93554c23d88f34f667f1979e4a1cee792af3
-F src/os_unix.c 0d91b28d57c0885fe97fb9020fd1091578066b5b
+F src/os_unix.c 5f7ee6c930084bcae48fd2caf4f73011d2c0795b
 F src/os_unix.h 5768d56d28240d3fe4537fac08cc85e4fb52279e
-F src/os_win.c 84c02837a6ec216a07e83a1d10d5a01c417bb489
+F src/os_win.c d6cb36287a13a75cbf0b7084399c7884a96c4340
 F src/os_win.h 41a946bea10f61c158ce8645e7646b29d44f122b
-F src/pager.c 9a6eefc192e3922c27bc0b18914b45dc9c348ffb
+F src/pager.c b89ea0f592e499ee6d6cda10b84688f8e47a05ba
 F src/pager.h f1b17bf848b3dce5d9afb2701186d3c9a8826f8c
 F src/parse.y 207ab04273ae13aa4a729b96008d294d5f334ab3
 F src/pragma.c 9cb8b94e7d38ba35a86037bd517d07ba9870b4b2
@@ -446,7 +446,7 @@ F www/tclsqlite.tcl bb0d1357328a42b1993d78573e587c6dcbc964b9
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl 97e2b5cd296f7d8057e11f44427dea8a4c2db513
-P e746832f5f3e1c58e6f6456866156824d23dd846
-R b1788f4ccc3dadea73c4b05cf92a2f56
+P e853067ec4db3eedfb4adcdd4172de2c55b9ac58
+R c174f33cfef400e7eb98f05642ec2e46
 U drh
-Z 5aae4929118467f5ff5f8ba730683d13
+Z 0685979faafd6228f2942fefc0f3e17a
diff --git a/manifest.uuid b/manifest.uuid
index 54efa6bc6a..2bad50ee5b 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-e853067ec4db3eedfb4adcdd4172de2c55b9ac58
\ No newline at end of file
+0fb9af1d6e20bf25511c6d2097937cc11137776e
\ No newline at end of file
diff --git a/src/os.c b/src/os.c
index b60831d6aa..77f5418645 100644
--- a/src/os.c
+++ b/src/os.c
@@ -76,7 +76,8 @@ int sqlite3OsCheckReservedLock(OsFile *id){
   return id->pMethod->xCheckReservedLock(id);
 }
 int sqlite3OsSectorSize(OsFile *id){
-  return id->pMethod->xSectorSize(id);
+  int (*xSectorSize)(OsFile*) = id->pMethod->xSectorSize;
+  return xSectorSize ? xSectorSize(id) : SQLITE_DEFAULT_SECTOR_SIZE;
 }
 
 #ifdef SQLITE_ENABLE_REDEF_IO
diff --git a/src/os.h b/src/os.h
index b0afe2f684..af4df325fa 100644
--- a/src/os.h
+++ b/src/os.h
@@ -73,6 +73,13 @@
 # define SET_FULLSYNC(x,y)
 #endif
 
+/*
+** The default size of a disk sector
+*/
+#ifndef SQLITE_DEFAULT_SECTOR_SIZE
+# define SQLITE_DEFAULT_SECTOR_SIZE 512
+#endif
+
 /*
 ** Temporary files are named starting with this prefix followed by 16 random
 ** alphanumeric characters, and no file extension. They are stored in the
diff --git a/src/os_os2.c b/src/os_os2.c
index 1dcf4b6729..8c28cccea3 100644
--- a/src/os_os2.c
+++ b/src/os_os2.c
@@ -743,7 +743,7 @@ static int os2LockState( OsFile *id ){
 ** same for both.
 */
 static int os2SectorSize(OsFile *id){
-  return PAGER_SECTOR_SIZE;
+  return SQLITE_DEFAULT_SECTOR_SIZE;
 }
 
 /*
diff --git a/src/os_unix.c b/src/os_unix.c
index be3a30a977..fc759d8017 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -2353,7 +2353,7 @@ static int unixLockState(OsFile *id){
 ** same for both.
 */
 static int unixSectorSize(OsFile *id){
-  return PAGER_SECTOR_SIZE;
+  return SQLITE_DEFAULT_SECTOR_SIZE;
 }
 
 /*
diff --git a/src/os_win.c b/src/os_win.c
index e5cf7ad5c1..ddab693e97 100644
--- a/src/os_win.c
+++ b/src/os_win.c
@@ -1466,7 +1466,7 @@ static int winLockState(OsFile *id){
 ** same for both.
 */
 static int winSectorSize(OsFile *id){
-  return PAGER_SECTOR_SIZE;
+  return SQLITE_DEFAULT_SECTOR_SIZE;
 }
 
 /*
diff --git a/src/pager.c b/src/pager.c
index 032823767c..82d7f4ecd2 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -18,7 +18,7 @@
 ** file simultaneously, or one process from reading the database while
 ** another is writing.
 **
-** @(#) $Id: pager.c,v 1.305 2007/03/29 17:28:15 danielk1977 Exp $
+** @(#) $Id: pager.c,v 1.306 2007/03/29 18:19:52 drh Exp $
 */
 #ifndef SQLITE_OMIT_DISKIO
 #include "sqliteInt.h"
@@ -1436,7 +1436,7 @@ end_playback:
   }
 
   /* The Pager.sectorSize variable may have been updated while rolling
-  ** back a journal created by a process with a different PAGER_SECTOR_SIZE
+  ** back a journal created by a process with a different sector size
   ** value. Reset it to the correct value for this process.
   */
   pPager->sectorSize = sqlite3OsSectorSize(pPager->fd);