Index: System.Data.SQLite/SQLite3.cs
==================================================================
--- System.Data.SQLite/SQLite3.cs
+++ System.Data.SQLite/SQLite3.cs
@@ -536,11 +536,11 @@
 
         if (n > 0) throw new SQLiteException(n, GetLastError());
 
         strRemain = UTF8ToString(ptr, len);
 
-        if (stmt != IntPtr.Zero) cmd = new SQLiteStatement(this, flags, new SQLiteStatementHandle(stmt), strSql.Substring(0, strSql.Length - strRemain.Length), previous);
+        if (stmt != IntPtr.Zero) cmd = new SQLiteStatement(this, flags, new SQLiteStatementHandle(_sql, stmt), strSql.Substring(0, strSql.Length - strRemain.Length), previous);
 
         return cmd;
       }
       finally
       {
@@ -1478,12 +1478,12 @@
 
         if (backup == IntPtr.Zero)
             throw new SQLiteException(ResultCode(), GetLastError());
 
         return new SQLiteBackup(
-            this, new SQLiteBackupHandle(backup), destHandle, zDestName,
-            sourceHandle, zSourceName);
+            this, new SQLiteBackupHandle(destHandle, backup),
+            destHandle, zDestName, sourceHandle, zSourceName);
     }
 
     /// <summary>
     /// Copies up to N pages from the source database to the destination
     /// database associated with the specified backup object.

Index: System.Data.SQLite/SQLiteBase.cs
==================================================================
--- System.Data.SQLite/SQLiteBase.cs
+++ System.Data.SQLite/SQLiteBase.cs
@@ -365,26 +365,32 @@
 #pragma warning disable 162
         GC.KeepAlive(hdl); /* NOTE: Unreachable code. */
 #pragma warning restore 162
     }
 
-    internal static void FinishBackup(IntPtr backup)
+    internal static void FinishBackup(SQLiteConnectionHandle hdl, IntPtr backup)
     {
-        if (backup == IntPtr.Zero) return;
-        int n = UnsafeNativeMethods.sqlite3_backup_finish(backup);
-        if (n > 0) throw new SQLiteException(n, null);
+        if ((hdl == null) || (backup == IntPtr.Zero)) return;
+        lock (hdl)
+        {
+            int n = UnsafeNativeMethods.sqlite3_backup_finish(backup);
+            if (n > 0) throw new SQLiteException(n, null);
+        }
     }
 
-    internal static void FinalizeStatement(IntPtr stmt)
+    internal static void FinalizeStatement(SQLiteConnectionHandle hdl, IntPtr stmt)
     {
-        if (stmt == IntPtr.Zero) return;
+        if ((hdl == null) || (stmt == IntPtr.Zero)) return;
+        lock (hdl)
+        {
 #if !SQLITE_STANDARD
-        int n = UnsafeNativeMethods.sqlite3_finalize_interop(stmt);
+            int n = UnsafeNativeMethods.sqlite3_finalize_interop(stmt);
 #else
-        int n = UnsafeNativeMethods.sqlite3_finalize(stmt);
+            int n = UnsafeNativeMethods.sqlite3_finalize(stmt);
 #endif
-        if (n > 0) throw new SQLiteException(n, null);
+            if (n > 0) throw new SQLiteException(n, null);
+        }
     }
 
     internal static void CloseConnection(SQLiteConnectionHandle hdl, IntPtr db)
     {
         if ((hdl == null) || (db == IntPtr.Zero)) return;

Index: System.Data.SQLite/UnsafeNativeMethods.cs
==================================================================
--- System.Data.SQLite/UnsafeNativeMethods.cs
+++ System.Data.SQLite/UnsafeNativeMethods.cs
@@ -1455,18 +1455,21 @@
   }
 
   // Provides finalization support for unmanaged SQLite statements.
   internal class SQLiteStatementHandle : CriticalHandle
   {
+    private SQLiteConnectionHandle cnn;
+
     public static implicit operator IntPtr(SQLiteStatementHandle stmt)
     {
       return (stmt != null) ? stmt.handle : IntPtr.Zero;
     }
 
-    internal SQLiteStatementHandle(IntPtr stmt)
+    internal SQLiteStatementHandle(SQLiteConnectionHandle cnn, IntPtr stmt)
       : this()
     {
+      this.cnn = cnn;
       SetHandle(stmt);
     }
 
     private SQLiteStatementHandle()
       : base(IntPtr.Zero)
@@ -1480,11 +1483,11 @@
 #if !PLATFORM_COMPACTFRAMEWORK
         IntPtr localHandle = Interlocked.Exchange(
           ref handle, IntPtr.Zero);
 
         if (localHandle != IntPtr.Zero)
-          SQLiteBase.FinalizeStatement(localHandle);
+          SQLiteBase.FinalizeStatement(cnn, localHandle);
 
 #if DEBUG && !NET_COMPACT_20
         try
         {
           Trace.WriteLine(String.Format(
@@ -1495,11 +1498,11 @@
         }
 #endif
 #else
         if (handle != IntPtr.Zero)
         {
-          SQLiteBase.FinalizeStatement(handle);
+          SQLiteBase.FinalizeStatement(cnn, handle);
           SetHandle(IntPtr.Zero);
         }
 #endif
 
 #if DEBUG
@@ -1549,18 +1552,21 @@
   }
 
   // Provides finalization support for unmanaged SQLite backup objects.
   internal class SQLiteBackupHandle : CriticalHandle
   {
+      private SQLiteConnectionHandle cnn;
+
       public static implicit operator IntPtr(SQLiteBackupHandle backup)
       {
           return (backup != null) ? backup.handle : IntPtr.Zero;
       }
 
-      internal SQLiteBackupHandle(IntPtr backup)
+      internal SQLiteBackupHandle(SQLiteConnectionHandle cnn, IntPtr backup)
           : this()
       {
+          this.cnn = cnn;
           SetHandle(backup);
       }
 
       private SQLiteBackupHandle()
           : base(IntPtr.Zero)
@@ -1574,11 +1580,11 @@
 #if !PLATFORM_COMPACTFRAMEWORK
               IntPtr localHandle = Interlocked.Exchange(
                   ref handle, IntPtr.Zero);
 
               if (localHandle != IntPtr.Zero)
-                  SQLiteBase.FinishBackup(localHandle);
+                  SQLiteBase.FinishBackup(cnn, localHandle);
 
 #if DEBUG && !NET_COMPACT_20
               try
               {
                   Trace.WriteLine(String.Format(
@@ -1589,11 +1595,11 @@
               }
 #endif
 #else
               if (handle != IntPtr.Zero)
               {
-                SQLiteBase.FinishBackup(handle);
+                SQLiteBase.FinishBackup(cnn, handle);
                 SetHandle(IntPtr.Zero);
               }
 #endif
 
 #if DEBUG