diff --git a/dlls/kernel32/tests/debugger.c b/dlls/kernel32/tests/debugger.c
index b7ec9e99ed3..fb5ea1581e2 100644
--- a/dlls/kernel32/tests/debugger.c
+++ b/dlls/kernel32/tests/debugger.c
@@ -1727,15 +1727,29 @@ static DWORD run_child_wait( char *cmd, HANDLE event )
     return exit_code;
 }
 
+static PROCESS_INFORMATION pi;
+static char *cmd;
+
+static DWORD WINAPI debug_and_exit(void *arg)
+{
+    STARTUPINFOA si = { sizeof(si) };
+    BOOL ret;
+
+    ret = CreateProcessA(NULL, cmd, NULL, NULL, TRUE, DEBUG_PROCESS, NULL, NULL, &si, &pi);
+    ok(ret, "CreateProcess failed, last error %#x.\n", GetLastError());
+    Sleep(200);
+    *(HANDLE *)arg = pDbgUiGetThreadDebugObject();
+    ExitThread(0);
+}
+
 static void test_kill_on_exit(const char *argv0)
 {
     static const char arguments[] = " debugger wait ";
     SECURITY_ATTRIBUTES sa = { sizeof(sa), NULL, TRUE };
     OBJECT_ATTRIBUTES attr = { sizeof(attr) };
     NTSTATUS status;
-    HANDLE event, debug;
-    DWORD exit_code;
-    char *cmd;
+    HANDLE event, debug, thread;
+    DWORD exit_code, tid;
     ULONG val;
 
     event = CreateEventW(&sa, FALSE, FALSE, NULL);
@@ -1784,6 +1798,26 @@ static void test_kill_on_exit(const char *argv0)
     exit_code = run_child_wait( cmd, event );
     ok( exit_code == STATUS_DEBUGGER_INACTIVE, "exit code = %08x\n", exit_code);
 
+    /* test that threads don't close the debug port on exit */
+    thread = CreateThread(NULL, 0, debug_and_exit, &debug, 0, &tid);
+    WaitForSingleObject( thread, 1000 );
+    ok( debug != 0, "no debug port\n" );
+    SetEvent( event );
+    WaitForSingleObject( pi.hProcess, 100 );
+    GetExitCodeProcess( pi.hProcess, &exit_code );
+    ok( exit_code == STILL_ACTIVE, "exit code = %08x\n", exit_code);
+    val = 0;
+    status = pNtSetInformationDebugObject( debug, DebugObjectKillProcessOnExitInformation,
+                                           &val, sizeof(val), NULL );
+    ok( !status, "NtSetInformationDebugObject failed %x\n", status );
+    CloseHandle( debug );
+    WaitForSingleObject( pi.hProcess, 1000 );
+    GetExitCodeProcess( pi.hProcess, &exit_code );
+    ok( exit_code == 0, "exit code = %08x\n", exit_code);
+    CloseHandle( pi.hProcess );
+    CloseHandle( pi.hThread );
+    CloseHandle( thread );
+
     heap_free(cmd);
 }
 
diff --git a/server/debugger.c b/server/debugger.c
index 927fe42929e..24cf33f92b4 100644
--- a/server/debugger.c
+++ b/server/debugger.c
@@ -488,7 +488,6 @@ static int debugger_attach( struct process *process, struct thread *debugger, st
         struct thread *renderer = console_get_renderer(debugger->process->console);
         if (renderer && renderer->process == process) goto error;
     }
-    if (!debugger->debug_obj) debugger->debug_obj = (struct debug_obj *)grab_object( debug_obj );
 
     suspend_process( process );
 
@@ -568,20 +567,6 @@ void generate_startup_debug_events( struct process *process, client_ptr_t entry
     }
 }
 
-/* a thread is exiting */
-void debug_exit_thread( struct thread *thread )
-{
-    struct debug_obj *debug_obj = thread->debug_obj;
-
-    if (debug_obj)  /* this thread is a debugger */
-    {
-        detach_debugged_processes( debug_obj,
-                                   (debug_obj->flags & DEBUG_KILL_ON_CLOSE) ? STATUS_DEBUGGER_INACTIVE : 0 );
-        release_object( thread->debug_obj );
-        thread->debug_obj = NULL;
-    }
-}
-
 /* create a debug object */
 DECL_HANDLER(create_debug_obj)
 {
diff --git a/server/object.h b/server/object.h
index 77d0594f99e..62f2cbafca6 100644
--- a/server/object.h
+++ b/server/object.h
@@ -215,7 +215,6 @@ extern void sock_init(void);
 extern void generate_debug_event( struct thread *thread, int code, const void *arg );
 extern void resume_delayed_debug_events( struct thread *thread );
 extern void generate_startup_debug_events( struct process *process, client_ptr_t entry );
-extern void debug_exit_thread( struct thread *thread );
 
 /* registry functions */
 
diff --git a/server/process.c b/server/process.c
index 95e030777c9..60562db326b 100644
--- a/server/process.c
+++ b/server/process.c
@@ -1261,7 +1261,6 @@ DECL_HANDLER(new_process)
     {
         process->debug_obj = debug_obj;
         process->debug_children = !(req->create_flags & DEBUG_ONLY_THIS_PROCESS);
-        if (!current->debug_obj) current->debug_obj = (struct debug_obj *)grab_object( debug_obj );
     }
     else if (parent->debug_children)
     {
diff --git a/server/thread.c b/server/thread.c
index fd3538c51f3..03b483d14ee 100644
--- a/server/thread.c
+++ b/server/thread.c
@@ -221,7 +221,6 @@ static inline void init_thread_structure( struct thread *thread )
     thread->context         = NULL;
     thread->teb             = 0;
     thread->entry_point     = 0;
-    thread->debug_obj       = NULL;
     thread->system_regs     = 0;
     thread->queue           = NULL;
     thread->wait            = NULL;
@@ -429,7 +428,6 @@ static void destroy_thread( struct object *obj )
     struct thread *thread = (struct thread *)obj;
     assert( obj->ops == &thread_ops );
 
-    assert( !thread->debug_obj );  /* cannot still be debugging something */
     list_remove( &thread->entry );
     cleanup_thread( thread );
     release_object( thread->process );
@@ -1266,7 +1264,6 @@ void kill_thread( struct thread *thread, int violent_death )
         violent_death = 0;
     }
     kill_console_processes( thread, 0 );
-    debug_exit_thread( thread );
     abandon_mutexes( thread );
     wake_up( &thread->obj, 0 );
     if (violent_death) send_thread_signal( thread, SIGQUIT );
diff --git a/server/thread.h b/server/thread.h
index a83309bc940..5f8eeeb3c50 100644
--- a/server/thread.h
+++ b/server/thread.h
@@ -54,7 +54,6 @@ struct thread
     struct process        *process;
     thread_id_t            id;            /* thread id */
     struct list            mutex_list;    /* list of currently owned mutexes */
-    struct debug_obj      *debug_obj;     /* debugger context if this thread is a debugger */
     unsigned int           system_regs;   /* which system regs have been set */
     struct msg_queue      *queue;         /* message queue */
     struct thread_wait    *wait;          /* current wait condition if sleeping */