Index: src/os_unix.c
==================================================================
--- src/os_unix.c
+++ src/os_unix.c
@@ -3173,11 +3173,11 @@
 };
 
 /*
 ** Constants used for locking
 */
-#define UNIX_SHM_BASE   ((18+SQLITE_SHM_NLOCK)*4)         /* first lock byte */
+#define UNIX_SHM_BASE   ((22+SQLITE_SHM_NLOCK)*4)         /* first lock byte */
 #define UNIX_SHM_DMS    (UNIX_SHM_BASE+SQLITE_SHM_NLOCK)  /* deadman switch */
 
 /*
 ** Apply posix advisory locks for all bytes from ofst through ofst+n-1.
 **

Index: src/os_win.c
==================================================================
--- src/os_win.c
+++ src/os_win.c
@@ -1263,11 +1263,11 @@
 };
 
 /*
 ** Constants used for locking
 */
-#define WIN_SHM_BASE   ((18+SQLITE_SHM_NLOCK)*4)        /* first lock byte */
+#define WIN_SHM_BASE   ((22+SQLITE_SHM_NLOCK)*4)        /* first lock byte */
 #define WIN_SHM_DMS    (WIN_SHM_BASE+SQLITE_SHM_NLOCK)  /* deadman switch */
 
 /*
 ** Apply advisory locks for all n bytes beginning at ofst.
 */