diff --git a/Makefile.msc b/Makefile.msc
index cb9c0cb15a..512de51c78 100644
--- a/Makefile.msc
+++ b/Makefile.msc
@@ -148,6 +148,13 @@ MEMDEBUG = 0
 WIN32HEAP = 0
 !ENDIF
 
+# Set this to non-0 to enable OSTRACE() macros, which can be useful when
+# debugging.
+#
+!IFNDEF OSTRACE
+OSTRACE = 0
+!ENDIF
+
 # Set this to one of the following values to enable various debugging
 # features.  Each level includes the debugging options from the previous
 # levels.  Currently, the recognized values for DEBUG are:
@@ -494,9 +501,9 @@ TCC = $(TCC) -DSQLITE_DEBUG
 RCC = $(RCC) -DSQLITE_DEBUG
 !ENDIF
 
-!IF $(DEBUG)>4
-TCC = $(TCC) -DSQLITE_DEBUG_OS_TRACE=1
-RCC = $(RCC) -DSQLITE_DEBUG_OS_TRACE=1
+!IF $(DEBUG)>4 || $(OSTRACE)!=0
+TCC = $(TCC) -DSQLITE_FORCE_OS_TRACE=1 -DSQLITE_DEBUG_OS_TRACE=1
+RCC = $(RCC) -DSQLITE_FORCE_OS_TRACE=1 -DSQLITE_DEBUG_OS_TRACE=1
 !ENDIF
 
 !IF $(DEBUG)>5
diff --git a/manifest b/manifest
index a6b688dba6..ae2d884573 100644
--- a/manifest
+++ b/manifest
@@ -1,9 +1,9 @@
-C Update\sthe\stest/fuzzdata1.txt\sfile\swith\sthe\slatest\scases\sdiscovered\sby\sAFL.
-D 2015-04-28T14:49:41.338
+C Improved\ssupport\sfor\sOSTRACE\son\sWindows.
+D 2015-04-29T00:35:07.945
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in e3268d234210842b4be0a6e2e1c5990999f1d9f4
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
-F Makefile.msc 0f859a8bbda8b3876ed2f257281db26ba9ad8398
+F Makefile.msc d80278757ef0b02d797d6ab98e07baf9c608b1a2
 F Makefile.vxworks e1b65dea203f054e71653415bd8f96dcaed47858
 F README.md d58e3bebc0a4145e0f2a87994015fdb575a8e866
 F VERSION 2e244662b71e6e68a5c29b014ebc5b7564f4cc5a
@@ -195,7 +195,7 @@ F src/journal.c b4124532212b6952f42eb2c12fa3c25701d8ba8d
 F src/legacy.c ba1863ea58c4c840335a84ec276fc2b25e22bc4e
 F src/lempar.c 7274c97d24bb46631e504332ccd3bd1b37841770
 F src/loadext.c 86bd4e2fccd520b748cba52492ab60c4a770f660
-F src/main.c 40e333960d53f7d50ee8ce09d40431c87ea653f2
+F src/main.c 6dc030204d80be177578210a90c912e1d9597126
 F src/malloc.c 6a370b83d54e4bbf6f94021221c2a311cff26a18
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c abe6ee469b6c5a35c7f22bfeb9c9bac664a1c987
@@ -212,10 +212,10 @@ F src/mutex_w32.c 61660ada28d8308ad190f444c2170c4f2a590c2f
 F src/notify.c 9711a7575036f0d3040ba61bc6e217f13a9888e7
 F src/os.c 8fd25588eeba74068d41102d26810e216999b6c8
 F src/os.h 3e57a24e2794a94d3cf2342c6d9a884888cd96bf
-F src/os_common.h 92815ed65f805560b66166e3583470ff94478f04
+F src/os_common.h abdb9a191a367793268fe553d25bab894e986a0e
 F src/os_setup.h c9d4553b5aaa6f73391448b265b89bed0b890faa
-F src/os_unix.c 5ed7e2e453c2980909a6b2c80dc55764b50819a8
-F src/os_win.c 03d27be3a20048ef52a648d5f0a15f5edda9f2a3
+F src/os_unix.c cf45d7b1cd27341ba8699e62c4902062b6297039
+F src/os_win.c c2f0b0b3541906e310588b9e95080df4df75b674
 F src/os_win.h eb7a47aa17b26b77eb97e4823f20a00b8bda12ca
 F src/pager.c 5283581c8ce8950ff483a0b3a3cab9cb4d25a21e
 F src/pager.h c3476e7c89cdf1c6914e50a11f3714e30b4e0a77
@@ -226,7 +226,7 @@ F src/pcache1.c 69d137620a305f814398bd29a0c998038c0695e9
 F src/pragma.c c1f4d012ea9f6b1ce52d341b2cd0ad72d560afd7
 F src/pragma.h 09c89bca58e9a44de2116cc8272b8d454657129f
 F src/prepare.c 1fffbdcd6f8a0173a8f70d71f22528f4c0e1e3d3
-F src/printf.c 08fa675c200aac29e561c6153f91f909ed17612f
+F src/printf.c 18df0da8c343dc4380f27a803858f2a4b81f1824
 F src/random.c ba2679f80ec82c4190062d756f22d0c358180696
 F src/resolve.c 13109bc3b5ab404446296efa17039640de5bc35d
 F src/rowset.c eccf6af6d620aaa4579bd3b72c1b6395d9e9fa1e
@@ -235,7 +235,7 @@ F src/shell.c 78eabce4c16c45e36fea2368f95118116399ba8a
 F src/sqlite.h.in ca27603a36fcacdaac5a19d8ee35aaff8ce8516f
 F src/sqlite3.rc 992c9f5fb8285ae285d6be28240a7e8d3a7f2bad
 F src/sqlite3ext.h 17d487c3c91b0b8c584a32fbeb393f6f795eea7d
-F src/sqliteInt.h 8abcea1295138f10ef8f7ed38db5f1b573b93ece
+F src/sqliteInt.h d6b2e99b3dd3f51ccc4b7c568d8b529d0fd5d07c
 F src/sqliteLimit.h 216557999cb45f2e3578ed53ebefe228d779cb46
 F src/status.c f266ad8a2892d659b74f0f50cb6a88b6e7c12179
 F src/table.c e7a09215315a978057fb42c640f890160dbcc45e
@@ -1255,7 +1255,8 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
 F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
-P 36e515261825be60ffdc73d13340d77cf377e8e1
-R db2aae636d49245c4e56d8069299efc5
+P f2063f5320f5a5d884f9c931eb91b7cc94945b92 9e593fb3dbc58e86f499ba4399530e3e760eb84d
+R 50bbfdab6cd5db4348f928cc10df10af
+T +closed 9e593fb3dbc58e86f499ba4399530e3e760eb84d
 U drh
-Z 6bb01ba2e8fe64ed97342e20664c6298
+Z 2fc3b10b7831d47e1437f4606a69806e
diff --git a/manifest.uuid b/manifest.uuid
index ea891cf9a3..6baed05a2b 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-f2063f5320f5a5d884f9c931eb91b7cc94945b92
\ No newline at end of file
+ca43812bde499a23244e2860d3ceddc97d29f09e
\ No newline at end of file
diff --git a/src/main.c b/src/main.c
index d9ee77fab2..ff5a1061b3 100644
--- a/src/main.c
+++ b/src/main.c
@@ -55,6 +55,18 @@ int sqlite3_libversion_number(void){ return SQLITE_VERSION_NUMBER; }
 */
 int sqlite3_threadsafe(void){ return SQLITE_THREADSAFE; }
 
+/*
+** When compiling the test fixture or with debugging enabled (on Win32),
+** this variable being set to non-zero will cause OSTRACE macros to emit
+** extra diagnostic information.
+*/
+#ifdef SQLITE_HAVE_OS_TRACE
+# ifndef SQLITE_DEBUG_OS_TRACE
+#   define SQLITE_DEBUG_OS_TRACE 0
+# endif
+  int sqlite3OSTrace = SQLITE_DEBUG_OS_TRACE;
+#endif
+
 #if !defined(SQLITE_OMIT_TRACE) && defined(SQLITE_ENABLE_IOTRACE)
 /*
 ** If the following function pointer is not NULL and if
@@ -1194,7 +1206,7 @@ void sqlite3RollbackAll(sqlite3 *db, int tripCode){
 ** Return a static string containing the name corresponding to the error code
 ** specified in the argument.
 */
-#if (defined(SQLITE_DEBUG) && SQLITE_OS_WIN) || defined(SQLITE_TEST)
+#if defined(SQLITE_NEED_ERR_NAME)
 const char *sqlite3ErrName(int rc){
   const char *zName = 0;
   int i, origRc = rc;
diff --git a/src/os_common.h b/src/os_common.h
index f6c3e7ff89..d18b95a5ff 100644
--- a/src/os_common.h
+++ b/src/os_common.h
@@ -29,16 +29,6 @@
 # error "The MEMORY_DEBUG macro is obsolete.  Use SQLITE_DEBUG instead."
 #endif
 
-#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
-# ifndef SQLITE_DEBUG_OS_TRACE
-#   define SQLITE_DEBUG_OS_TRACE 0
-# endif
-  int sqlite3OSTrace = SQLITE_DEBUG_OS_TRACE;
-# define OSTRACE(X)          if( sqlite3OSTrace ) sqlite3DebugPrintf X
-#else
-# define OSTRACE(X)
-#endif
-
 /*
 ** Macros for performance tracing.  Normally turned off.  Only works
 ** on i486 hardware.
diff --git a/src/os_unix.c b/src/os_unix.c
index 188c025336..93657f6898 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -641,7 +641,7 @@ static int unixMutexHeld(void) {
 #endif
 
 
-#if defined(SQLITE_TEST) && defined(SQLITE_DEBUG)
+#ifdef SQLITE_HAVE_OS_TRACE
 /*
 ** Helper function for printing out trace information from debugging
 ** binaries. This returns the string representation of the supplied
diff --git a/src/os_win.c b/src/os_win.c
index ef2f553f33..3a8c4cbdbf 100644
--- a/src/os_win.c
+++ b/src/os_win.c
@@ -2757,7 +2757,7 @@ static int winSync(sqlite3_file *id, int flags){
   BOOL rc;
 #endif
 #if !defined(NDEBUG) || !defined(SQLITE_NO_SYNC) || \
-    (defined(SQLITE_TEST) && defined(SQLITE_DEBUG))
+    defined(SQLITE_HAVE_OS_TRACE)
   /*
   ** Used when SQLITE_NO_SYNC is not defined and by the assert() and/or
   ** OSTRACE() macros.
@@ -3434,7 +3434,7 @@ struct winShmNode {
   int nRef;                  /* Number of winShm objects pointing to this */
   winShm *pFirst;            /* All winShm objects pointing to this */
   winShmNode *pNext;         /* Next in list of all winShmNode objects */
-#ifdef SQLITE_DEBUG
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
   u8 nextShmId;              /* Next available winShm.id value */
 #endif
 };
@@ -3465,7 +3465,7 @@ struct winShm {
   u8 hasMutex;               /* True if holding the winShmNode mutex */
   u16 sharedMask;            /* Mask of shared locks held */
   u16 exclMask;              /* Mask of exclusive locks held */
-#ifdef SQLITE_DEBUG
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
   u8 id;                     /* Id of this connection with its winShmNode */
 #endif
 };
@@ -3656,7 +3656,7 @@ static int winOpenSharedMemory(winFile *pDbFd){
 
   /* Make the new connection a child of the winShmNode */
   p->pShmNode = pShmNode;
-#ifdef SQLITE_DEBUG
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
   p->id = pShmNode->nextShmId++;
 #endif
   pShmNode->nRef++;
diff --git a/src/printf.c b/src/printf.c
index 1a978dc5ca..d4063174ac 100644
--- a/src/printf.c
+++ b/src/printf.c
@@ -1059,7 +1059,7 @@ void sqlite3_log(int iErrCode, const char *zFormat, ...){
   }
 }
 
-#if defined(SQLITE_DEBUG)
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
 /*
 ** A version of printf() that understands %lld.  Used for debugging.
 ** The printf() built into some versions of windows does not understand %lld
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index f34645fa8d..231bc09768 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -362,6 +362,32 @@
 # define NEVER(X)       (X)
 #endif
 
+/*
+** Declarations used for tracing the operating system interfaces.
+*/
+#if defined(SQLITE_FORCE_OS_TRACE) || defined(SQLITE_TEST) || \
+    (defined(SQLITE_DEBUG) && SQLITE_OS_WIN)
+  extern int sqlite3OSTrace;
+# define OSTRACE(X)          if( sqlite3OSTrace ) sqlite3DebugPrintf X
+# define SQLITE_HAVE_OS_TRACE
+#else
+# define OSTRACE(X)
+# undef  SQLITE_HAVE_OS_TRACE
+#endif
+
+/*
+** Is the sqlite3ErrName() function needed in the build?  Currently,
+** it is needed by "mutex_w32.c" (when debugging), "os_win.c" (when
+** OSTRACE is enabled), and by several "test*.c" files (which are
+** compiled using SQLITE_TEST).
+*/
+#if defined(SQLITE_HAVE_OS_TRACE) || defined(SQLITE_TEST) || \
+    (defined(SQLITE_DEBUG) && SQLITE_OS_WIN)
+# define SQLITE_NEED_ERR_NAME
+#else
+# undef  SQLITE_NEED_ERR_NAME
+#endif
+
 /*
 ** Return true (non-zero) if the input is an integer that is too large
 ** to fit in 32-bits.  This macro is used inside of various testcase()
@@ -3153,7 +3179,7 @@ void sqlite3XPrintf(StrAccum*, u32, const char*, ...);
 char *sqlite3MPrintf(sqlite3*,const char*, ...);
 char *sqlite3VMPrintf(sqlite3*,const char*, va_list);
 char *sqlite3MAppendf(sqlite3*,char*,const char*,...);
-#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
+#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
   void sqlite3DebugPrintf(const char*, ...);
 #endif
 #if defined(SQLITE_TEST)
@@ -3500,7 +3526,7 @@ void *sqlite3HexToBlob(sqlite3*, const char *z, int n);
 u8 sqlite3HexToInt(int h);
 int sqlite3TwoPartName(Parse *, Token *, Token *, Token **);
 
-#if defined(SQLITE_TEST) 
+#if defined(SQLITE_NEED_ERR_NAME)
 const char *sqlite3ErrName(int);
 #endif