diff --git a/manifest b/manifest
index 9d22529099..0b380a8a0e 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Replace\sJNI's\sper-db-instance\sstate\stracking\swith\sthe\snew\ssqlite3_set/get_clientdata().
-D 2023-08-30T18:45:42.722
+C Use\smutexes\sto\smake\ssqlite3_set_clientdata()\sand\ssqlite3_get_clientdata()\nthreadsafe.
+D 2023-08-30T18:51:26.770
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -668,7 +668,7 @@ F src/insert.c 3f0a94082d978bbdd33c38fefea15346c6c6bffb70bc645a71dc0f1f87dd3276
 F src/json.c ae840f87b418f039f5d336b488933d09396bd31e6b31e855b93055ccaee4e255
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 98cfba10989b3da6f1807ad42444017742db7f100a54f1032af7a8b1295912c0
-F src/main.c 3eb8c45e05829649bb15aea10cd04cbc1a116438e6a129de025b70dba73b922a
+F src/main.c 2adfb1973ee495977f8c75d6590aae9882161d5f8749b46621299656a2df0cc6
 F src/malloc.c 47b82c5daad557d9b963e3873e99c22570fb470719082c6658bf64e3012f7d23
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c 3bb59158c38e05f6270e761a9f435bf19827a264c13d1631c58b84bdc96d73b2
@@ -2115,8 +2115,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 57e31e6b10b2aa68b6039914d191819bae0aa60999a99d5ef23ca18128b72e0e
-R 936a89e0748a165d8e043fd6221f1b2f
-U stephan
-Z 84bdefd82082ec3e33e8b63200701207
+P e7c11d34ee2eebdca4d9db1496bbb4152e4c62745c083ad5e0337733e8d1254e
+R 3f04e2f3da46f99baea85816871f54e6
+U drh
+Z 4a72dec53887e83eac398e1a9fd59cf2
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index 28927e9512..14a82559d3 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-e7c11d34ee2eebdca4d9db1496bbb4152e4c62745c083ad5e0337733e8d1254e
\ No newline at end of file
+443ea20ddb0f3bf5d77ef59cd4678f0e32d7da328002bb44d6fc080a53a37e29
\ No newline at end of file
diff --git a/src/main.c b/src/main.c
index 257b9b7600..6525fc0d71 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3723,8 +3723,16 @@ int sqlite3_collation_needed16(
 */
 void *sqlite3_get_clientdata(sqlite3 *db, const char *zName){
   DbClientData *p;
-  for(p=db->pDbData; p && strcmp(p->zName,zName); p=p->pNext){}
-  return p ? p->pData : 0;
+  sqlite3_mutex_enter(db->mutex);
+  for(p=db->pDbData; p; p=p->pNext){
+    if( strcmp(p->zName, zName)==0 ){
+      void *pResult = p->pData;
+      sqlite3_mutex_leave(db->mutex);
+      return pResult;
+    }
+  }
+  sqlite3_mutex_leave(db->mutex);
+  return 0;
 }
 
 /*
@@ -3737,6 +3745,7 @@ int sqlite3_set_clientdata(
   void (*xDestructor)(void*)     /* Destructor */
 ){
   DbClientData *p, **pp;
+  sqlite3_mutex_enter(db->mutex);
   pp = &db->pDbData;
   for(p=db->pDbData; p && strcmp(p->zName,zName); p=p->pNext){
     pp = &p->pNext;
@@ -3747,15 +3756,18 @@ int sqlite3_set_clientdata(
     if( pData==0 ){
       *pp = p->pNext;
       sqlite3_free(p);
+      sqlite3_mutex_leave(db->mutex);
       return SQLITE_OK;
     }
   }else if( pData==0 ){
+    sqlite3_mutex_leave(db->mutex);
     return SQLITE_OK;
   }else{
     size_t n = strlen(zName);
     p = sqlite3_malloc64( sizeof(DbClientData)+n+1 );
     if( p==0 ){
       if( xDestructor ) xDestructor(pData);
+      sqlite3_mutex_leave(db->mutex);
       return SQLITE_NOMEM;
     }
     memcpy(p->zName, zName, n+1);
@@ -3764,6 +3776,7 @@ int sqlite3_set_clientdata(
   }
   p->pData = pData;
   p->xDestructor = xDestructor;
+  sqlite3_mutex_leave(db->mutex);
   return SQLITE_OK;
 }