diff --git a/rtl/inc/heap.inc b/rtl/inc/heap.inc
index bdc11f5c08..0d4f09642a 100644
--- a/rtl/inc/heap.inc
+++ b/rtl/inc/heap.inc
@@ -1313,4 +1313,26 @@ begin
   fillchar(internal_status,sizeof(internal_status),0);
 end;
 
+
+procedure FinalizeHeap;
+var
+  poc : poschunk;
+  i : longint;
+begin
+{$ifdef HAS_SYSOSFREE}
+  for i:=low(freelists_free_chunk) to high(freelists_free_chunk) do
+    if freelists_free_chunk[i] then
+      SysOSFree(freelists_fixed[i]^.poc,freelists_fixed[i]^.poc^.size);
+  while assigned(freeoslist) do
+    begin
+      poc:=freeoslist^.next;
+      SysOSFree(freeoslist, freeoslist^.size);
+      dec(freeoslistcount);
+      freeoslist:=poc;
+    end;
+{$endif HAS_SYSOSFREE}
+  { release mutex }
+  MemoryMutexManager.MutexDone;
+end;
+
 {$endif HAS_MEMORYMANAGER}
diff --git a/rtl/inc/system.inc b/rtl/inc/system.inc
index 0535ae4639..8952dbb203 100644
--- a/rtl/inc/system.inc
+++ b/rtl/inc/system.inc
@@ -663,10 +663,12 @@ end;
 *****************************************************************************}
 
 Procedure system_exit;forward;
+Procedure FinalizeHeap;forward;
 
 Procedure InternalExit;
 var
   current_exit : Procedure;
+  i : longint;
 Begin
   while exitProc<>nil Do
    Begin
@@ -691,6 +693,12 @@ Begin
   Flush(ErrOutput);
   Flush(StdOut);
   Flush(StdErr);
+  { finally release the heap if possible, especially
+    important for DLLs }
+  for i:=0 to argc do
+    sysfreemem(argv[i]);
+  sysfreemem(argv);
+  FinalizeHeap;
 End;
 
 
diff --git a/rtl/win32/system.pp b/rtl/win32/system.pp
index 908647fcce..61c14ce0c6 100644
--- a/rtl/win32/system.pp
+++ b/rtl/win32/system.pp
@@ -377,7 +377,11 @@ begin
    begin
      Close(stderr);
      Close(stdout);
+     Close(erroutput);
+     Close(Input);
+     Close(Output);
      { what about Input and Output ?? PM }
+     { now handled, FPK }
    end;
   remove_exception_handlers;
 
@@ -466,7 +470,7 @@ var
          end;
        DLL_THREAD_ATTACH :
          begin
-           inc(Thread_count);
+           inclocked(Thread_count);
 {$warning Allocate Threadvars !}
            if assigned(Dll_Thread_Attach_Hook) then
              Dll_Thread_Attach_Hook(DllParam);
@@ -474,7 +478,7 @@ var
          end;
        DLL_THREAD_DETACH :
          begin
-           dec(Thread_count);
+           declocked(Thread_count);
            if assigned(Dll_Thread_Detach_Hook) then
              Dll_Thread_Detach_Hook(DllParam);
 {$warning Release Threadvars !}
@@ -484,9 +488,7 @@ var
          begin
            Dll_entry:=true; { return value is ignored }
            If SetJmp(DLLBuf) = 0 then
-             begin
-               FPC_DO_EXIT;
-             end;
+             FPC_Do_Exit;
            if assigned(Dll_Process_Detach_Hook) then
              Dll_Process_Detach_Hook(DllParam);
          end;
@@ -1237,5 +1239,5 @@ begin
   errno:=0;
   initvariantmanager;
   initwidestringmanager;
-  InitWin32Widestrings
+  InitWin32Widestrings;
 end.
diff --git a/rtl/win64/system.pp b/rtl/win64/system.pp
index 82e30b3f90..dd104e905b 100644
--- a/rtl/win64/system.pp
+++ b/rtl/win64/system.pp
@@ -458,7 +458,7 @@ var
          end;
        DLL_THREAD_ATTACH :
          begin
-           inc(Thread_count);
+           inclocked(Thread_count);
 {$warning Allocate Threadvars !}
            if assigned(Dll_Thread_Attach_Hook) then
              Dll_Thread_Attach_Hook(DllParam);
@@ -466,7 +466,7 @@ var
          end;
        DLL_THREAD_DETACH :
          begin
-           dec(Thread_count);
+           declocked(Thread_count);
            if assigned(Dll_Thread_Detach_Hook) then
              Dll_Thread_Detach_Hook(DllParam);
 {$warning Release Threadvars !}
diff --git a/rtl/wince/system.pp b/rtl/wince/system.pp
index d2f97d909d..12d8fbc42a 100644
--- a/rtl/wince/system.pp
+++ b/rtl/wince/system.pp
@@ -220,17 +220,17 @@ end;
 {$ifdef CPUARM}
 
 {$define FPC_SYSTEM_HAS_INT}
-function floor(d : double) : double; 
+function floor(d : double) : double;
    cdecl;external 'coredll' name 'floor';
 
-function ceil(d : double) : double; 
+function ceil(d : double) : double;
    cdecl;external 'coredll' name 'ceil';
 
 function fpc_int_real(d: ValReal): ValReal;compilerproc;
 begin
   if d > 0 then
     fpc_int_real:=floor(d)
-  else  
+  else
     fpc_int_real:=ceil(d);
 end;
 
@@ -564,7 +564,7 @@ var
   Fargc: longint;
   Fargv: ppchar;
   FCmdLine: PChar;
-  
+
 procedure setup_arguments;
 var
   arglen,
@@ -814,10 +814,13 @@ begin
   if IsLibrary then
     exit;
 //    ExitDLL(ExitCode);
-  if not IsConsole then begin
-    Close(stderr);
-    Close(stdout);
-    { what about Input and Output ?? PM }
+  if not IsConsole then
+    begin
+      Close(stderr);
+      Close(stdout);
+      Close(erroutput);
+      Close(Input);
+      Close(Output);
   end;
   ExitThread(exitcode);
 end;
@@ -859,21 +862,21 @@ begin
        end;
      DLL_THREAD_ATTACH :
        begin
-         inc(Thread_count);
+         inclocked(Thread_count);
 {$warning Allocate Threadvars !}
          if assigned(Dll_Thread_Attach_Hook) then
            Dll_Thread_Attach_Hook(DllParam);
        end;
      DLL_THREAD_DETACH :
        begin
-         dec(Thread_count);
+         declocked(Thread_count);
          if assigned(Dll_Thread_Detach_Hook) then
            Dll_Thread_Detach_Hook(DllParam);
 {$warning Release Threadvars !}
        end;
      DLL_PROCESS_DETACH :
        begin
-         FPC_DO_EXIT;
+         FPC_Do_Exit;
          if assigned(Dll_Process_Detach_Hook) then
            Dll_Process_Detach_Hook(DllParam);
        end;