diff --git a/manifest b/manifest
index baf7f7a7a9..af5ff072b4 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Allow\sthe\sWin32\snative\sheap\sflags\sto\sbe\soverridden\sat\scompile-time.
-D 2011-08-26T01:32:24.991
+C Disable\schecking\sthe\swinMemData\sstructure\ssignature\swhen\scompiled\swith\sNDEBUG.
+D 2011-08-26T01:45:50.307
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 8c930e7b493d59099ea1304bd0f2aed152eb3315
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -166,7 +166,7 @@ F src/os.h 9dbed8c2b9c1f2f2ebabc09e49829d4777c26bf9
 F src/os_common.h 65a897143b64667d23ed329a7984b9b405accb58
 F src/os_os2.c 4a75888ba3dfc820ad5e8177025972d74d7f2440
 F src/os_unix.c 81341980c52a44106b10c1e28a0d5c5247476452
-F src/os_win.c dc2e61b0727989a796482471e1e9caab890005ea
+F src/os_win.c 86bcb5bd0386c761c764c3383879469346da3a14
 F src/pager.c 120550e7ef01dafaa2cbb4a0528c0d87c8f12b41
 F src/pager.h 3f8c783de1d4706b40b1ac15b64f5f896bcc78d1
 F src/parse.y 12b7ebd61ea54f0e1b1083ff69cc2c8ce9353d58
@@ -961,7 +961,7 @@ F tool/symbols.sh caaf6ccc7300fd43353318b44524853e222557d5
 F tool/tostr.awk 11760e1b94a5d3dcd42378f3cc18544c06cfa576
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
 F tool/warnings.sh b7fdb2cc525f5ef4fa43c80e771636dd3690f9d2
-P 401859236b0d97bde82b11f32efce6eb9d490941
-R 35801e696f9647a4182ac9bf0b1942c5
+P 1c2ecec8e7320bc5b532b3107005fb7f0370f25c
+R 02977b3b753ae039e380bcd8a52f086a
 U mistachkin
-Z affee667f35124b9dd9a06a0543d989b
+Z 4992e9cb9a64a1646ed5db3855348839
diff --git a/manifest.uuid b/manifest.uuid
index 06e3e2ac82..8b8b11c9d4 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-1c2ecec8e7320bc5b532b3107005fb7f0370f25c
\ No newline at end of file
+50edc2f9141bd13277119afd129387029ebe5c01
\ No newline at end of file
diff --git a/src/os_win.c b/src/os_win.c
index 2af1dce8a5..02a7a0c622 100644
--- a/src/os_win.c
+++ b/src/os_win.c
@@ -153,16 +153,30 @@ struct winFile {
 */
 typedef struct winMemData winMemData;
 struct winMemData {
+#ifndef NDEBUG
   u32 magic;    /* Magic number to detect structure corruption. */
+#endif
   HANDLE hHeap; /* The handle to our heap. */
   BOOL bOwned;  /* Do we own the heap (i.e. destroy it on shutdown)? */
 };
 
+#ifndef NDEBUG
 #define WINMEM_MAGIC     0x42b2830b
+#endif
 
-static struct winMemData win_mem_data = { WINMEM_MAGIC, NULL, FALSE };
+static struct winMemData win_mem_data = {
+#ifndef NDEBUG
+  WINMEM_MAGIC,
+#endif
+  NULL, FALSE
+};
 
+#ifndef NDEBUG
 #define winMemAssertMagic() assert( win_mem_data.magic==WINMEM_MAGIC )
+#else
+#define winMemAssertMagic()
+#endif
+
 #define winMemGetHeap() win_mem_data.hHeap
 
 static void *winMemMalloc(int nBytes);