Index: src/backup.c
==================================================================
--- src/backup.c
+++ src/backup.c
@@ -416,10 +416,19 @@
       int nDestTruncate;
   
       if( p->pDestDb ){
         sqlite3ResetInternalSchema(p->pDestDb, -1);
       }
+
+      if( destMode==PAGER_JOURNALMODE_WAL ){
+        /* This call cannot fail. The success of the BtreeUpdateMeta() 
+        ** method above indicates that a write transaction has been opened 
+        ** and page 1 is already dirty. Therefore this always succeeds.
+        */
+        TESTONLY(int rc2 =) sqlite3BtreeSetVersion(p->pDest, 2);
+        assert( rc2==SQLITE_OK );
+      }
 
       /* Set nDestTruncate to the final number of pages in the destination
       ** database. The complication here is that the destination page
       ** size may be different to the source page size. 
       **

Index: src/btree.c
==================================================================
--- src/btree.c
+++ src/btree.c
@@ -8147,11 +8147,10 @@
 */
 int sqlite3BtreeSetVersion(Btree *pBtree, int iVersion){
   BtShared *pBt = pBtree->pBt;
   int rc;                         /* Return code */
  
-  assert( pBtree->inTrans==TRANS_NONE );
   assert( iVersion==1 || iVersion==2 );
 
   /* If setting the version fields to 1, do not automatically open the
   ** WAL connection, even if the version fields are currently set to 2.
   */

Index: test/walbak.test
==================================================================
--- test/walbak.test
+++ test/walbak.test
@@ -77,10 +77,13 @@
 } [list 1024 [wal_file_size 6 1024]]
 do_test walbak-1.6 {
   execsql { PRAGMA wal_checkpoint }
   list [file size test.db] [file size test.db-wal]
 } [list [expr 3*1024] [wal_file_size 6 1024]]
+do_test walbak-1.6.1 {
+  hexio_read test.db 18 2
+} {0202}
 do_test walbak-1.7 {
   execsql { 
     CREATE TABLE t2(a, b);
     INSERT INTO t2 SELECT * FROM t1;
     DROP TABLE t1;
@@ -268,12 +271,87 @@
     sqlite3_backup B db main db2 main
     B step 10000
     B finish
     execsql { SELECT * FROM t1 }
   } {1 2 3 4 5 6 7 8}
+
+  # Check that [db] is still in WAL mode.
+  do_test walbak-3.$tn.5 {
+    execsql { PRAGMA journal_mode }
+  } {wal}
+  do_test walbak-3.$tn.6 {
+    execsql { PRAGMA wal_checkpoint }
+    hexio_read test.db 18 2
+  } {0202}
+
+  # If it was not an in-memory database, check that [db2] is still in
+  # rollback mode.
+  if {[file exists test.db2]} {
+    do_test walbak-3.$tn.7 {
+      execsql { PRAGMA journal_mode } db2
+    } {wal}
+    do_test walbak-3.$tn.8 {
+      execsql { PRAGMA wal_checkpoint }
+      hexio_read test.db 18 2
+    } {0202}
+  }
 
   db  close
   db2 close
 }
+
+#-------------------------------------------------------------------------
+# Test that the following holds when a backup operation is run:
+#
+#   Source  |  Destination inital  |  Destination final
+#   ---------------------------------------------------
+#   Rollback   Rollback               Rollback
+#   Rollback   WAL                    WAL
+#   WAL        Rollback               WAL
+#   WAL        WAL                    WAL
+#
+foreach {tn src dest dest_final} {
+  1   delete    delete    delete
+  2   delete    wal       wal
+  3   wal       delete    wal
+  4   wal       wal       wal
+} {
+  catch { db close } 
+  catch { db2 close } 
+  forcedelete test.db test.db2
+
+  do_test walbak-4.$tn.1 {
+    sqlite3 db test.db
+    db eval "PRAGMA journal_mode = $src"
+    db eval {
+      CREATE TABLE t1(a, b);
+      INSERT INTO t1 VALUES('I', 'II');
+      INSERT INTO t1 VALUES('III', 'IV');
+    }
+
+    sqlite3 db2 test.db2
+    db2 eval "PRAGMA journal_mode = $dest"
+    db2 eval {
+      CREATE TABLE t2(x, y);
+      INSERT INTO t2 VALUES('1', '2');
+      INSERT INTO t2 VALUES('3', '4');
+    }
+  } {}
+
+  do_test walbak-4.$tn.2 { execsql { PRAGMA journal_mode } db  } $src
+  do_test walbak-4.$tn.3 { execsql { PRAGMA journal_mode } db2 } $dest
+
+  do_test walbak-4.$tn.4 { db backup test.db2 } {}
+  do_test walbak-4.$tn.5 {
+    execsql { SELECT * FROM t1 } db2
+  } {I II III IV}
+  do_test walbak-4.$tn.5 { execsql { PRAGMA journal_mode } db2 } $dest_final
+
+
+  db2 close
+  do_test walbak-4.$tn.6 { file exists test.db2-wal } 0
+  sqlite3 db2 test.db2
+  do_test walbak-4.$tn.7 { execsql { PRAGMA journal_mode } db2 } $dest_final
+}
 
 
 finish_test