Index: ext/misc/zipfile.c
==================================================================
--- ext/misc/zipfile.c
+++ ext/misc/zipfile.c
@@ -1522,11 +1522,11 @@
   int nData = 0;                  /* Size of pData buffer in bytes */
   int iMethod = 0;                /* Compression method for new entry */
   u8 *pFree = 0;                  /* Free this */
   char *zFree = 0;                /* Also free this */
   ZipfileEntry *pOld = 0;
-  int bUpdate = 0;
+  int bUpdate = 0;                /* True for an update that modifies "name" */
   int bIsDir = 0;
   u32 iCrc32 = 0;
 
   if( pTab->pWriteFd==0 ){
     rc = zipfileBegin(pVtab);

Index: test/zipfile2.test
==================================================================
--- test/zipfile2.test
+++ test/zipfile2.test
@@ -207,9 +207,33 @@
   set hex [string map {6e6f7461646972 6e6f746164692f} $hex] 
   set blob2 [binary decode hex $hex]
 
   execsql { SELECT name, data IS NULL FROM zipfile($blob2) }
 } {notadi/ 1}
+
+#-------------------------------------------------------------------------
+# Test that duplicate entries may not be created using UPDATE
+# statements.
+#
+forcedelete test.zip
+do_execsql_test 6.0 {
+  CREATE VIRTUAL TABLE temp.zip USING zipfile('test.zip'); 
+  INSERT INTO temp.zip (name,data) VALUES ('test1','test'); 
+  INSERT INTO temp.zip (name,data) VALUES ('test2','test'); 
+}
+do_catchsql_test 6.1 {
+  UPDATE temp.zip SET name='test1' WHERE name='test2'
+} {1 {duplicate name: "test1"}}
+
+forcedelete test.zip
+do_catchsql_test 6.2 {
+  DROP TABLE zip;
+  CREATE VIRTUAL TABLE temp.zip USING zipfile('test.zip'); 
+  INSERT INTO temp.zip (name,data) VALUES ('test','test'); 
+  UPDATE  temp.zip set name=name||'new' where name='test'; 
+  INSERT INTO temp.zip (name,data) VALUES ('test','test'); 
+  UPDATE  temp.zip set name=name||'new' where name='test'; 
+} {1 {duplicate name: "testnew"}}
 
 
 finish_test