diff --git a/dlls/dbghelp/cpu_i386.c b/dlls/dbghelp/cpu_i386.c
index 864b7f76643..45b3bd95df6 100644
--- a/dlls/dbghelp/cpu_i386.c
+++ b/dlls/dbghelp/cpu_i386.c
@@ -213,16 +213,16 @@ static BOOL i386_stack_walk(struct cpu_stack_walk *csw, STACKFRAME64 *frame,
         /* Init done */
         set_curr_mode((frame->AddrPC.Mode == AddrModeFlat) ? stm_32bit : stm_16bit);
 
-        /* cur_switch holds address of WOW32Reserved field in TEB in debuggee
+        /* cur_switch holds address of SystemReserved1[0] field in TEB in debuggee
          * address space
          */
         if (NtQueryInformationThread(csw->hThread, ThreadBasicInformation, &info,
                                      sizeof(info), NULL) == STATUS_SUCCESS)
         {
-            curr_switch = (DWORD_PTR)info.TebBaseAddress + FIELD_OFFSET(TEB, WOW32Reserved);
+            curr_switch = (DWORD_PTR)info.TebBaseAddress + FIELD_OFFSET(TEB, SystemReserved1);
             if (!sw_read_mem(csw, curr_switch, &p, sizeof(p)))
             {
-                WARN("Can't read TEB:WOW32Reserved\n");
+                WARN("Can't read TEB:SystemReserved1\n");
                 goto done_err;
             }
             next_switch = p;
diff --git a/dlls/krnl386.exe16/kernel16_private.h b/dlls/krnl386.exe16/kernel16_private.h
index 8c93b1dc0a2..279058ac68f 100644
--- a/dlls/krnl386.exe16/kernel16_private.h
+++ b/dlls/krnl386.exe16/kernel16_private.h
@@ -298,6 +298,7 @@ struct tagSYSLEVEL;
 
 struct kernel_thread_data
 {
+    SEGPTR              stack;          /* 16-bit stack pointer */
     WORD                stack_sel;      /* 16-bit stack selector */
     WORD                htask16;        /* Win16 task handle */
     DWORD               sys_count[4];   /* syslevel mutex entry counters */
diff --git a/dlls/krnl386.exe16/thunk.c b/dlls/krnl386.exe16/thunk.c
index ad2c52fab46..98dbf31a770 100644
--- a/dlls/krnl386.exe16/thunk.c
+++ b/dlls/krnl386.exe16/thunk.c
@@ -1229,7 +1229,7 @@ void WINAPI __regs_K32Thk1632Prolog( CONTEXT *context )
       DWORD argSize = context->Ebp - context->Esp;
       char *stack16 = (char *)context->Esp - 4;
       STACK16FRAME *frame16 = (STACK16FRAME *)stack16 - 1;
-      STACK32FRAME *frame32 = NtCurrentTeb()->WOW32Reserved;
+      STACK32FRAME *frame32 = (STACK32FRAME *)kernel_get_thread_data()->stack;
       char *stack32 = (char *)frame32 - argSize;
       WORD  stackSel  = SELECTOROF(frame32->frame16);
       DWORD stackBase = GetSelectorBase(stackSel);
@@ -1282,7 +1282,7 @@ void WINAPI __regs_K32Thk1632Epilog( CONTEXT *context )
       TRACE("before SYSTHUNK hack: EBP: %08x ESP: %08x cur_stack: %04x:%04x\n",
             context->Ebp, context->Esp, CURRENT_SS, CURRENT_SP);
 
-      NtCurrentTeb()->WOW32Reserved = frame16->frame32;
+      kernel_get_thread_data()->stack = (SEGPTR)frame16->frame32;
 
       context->Esp = (DWORD)stack16 + nArgsPopped;
       context->Ebp = frame16->ebp;
diff --git a/dlls/krnl386.exe16/wowthunk.c b/dlls/krnl386.exe16/wowthunk.c
index 2b4deb34e99..73d1565c573 100644
--- a/dlls/krnl386.exe16/wowthunk.c
+++ b/dlls/krnl386.exe16/wowthunk.c
@@ -127,7 +127,7 @@ static DWORD call16_handler( EXCEPTION_RECORD *record, EXCEPTION_REGISTRATION_RE
     {
         /* unwinding: restore the stack pointer in the TEB, and leave the Win16 mutex */
         STACK32FRAME *frame32 = CONTAINING_RECORD(frame, STACK32FRAME, frame);
-        NtCurrentTeb()->WOW32Reserved = (void *)frame32->frame16;
+        kernel_get_thread_data()->stack = frame32->frame16;
         _LeaveWin16Lock();
     }
     else if (record->ExceptionCode == EXCEPTION_ACCESS_VIOLATION ||
diff --git a/dlls/ntdll/unix/signal_i386.c b/dlls/ntdll/unix/signal_i386.c
index 58b79940773..eb4a6653f5e 100644
--- a/dlls/ntdll/unix/signal_i386.c
+++ b/dlls/ntdll/unix/signal_i386.c
@@ -630,7 +630,7 @@ static inline void *init_handler( const ucontext_t *sigcontext )
          * SS is still non-system segment. This is why both CS and SS
          * are checked.
          */
-        return teb->WOW32Reserved;
+        return teb->SystemReserved1[0];
     }
     return (void *)(ESP_sig(sigcontext) & ~3);
 }
diff --git a/dlls/toolhelp.dll16/toolhelp.c b/dlls/toolhelp.dll16/toolhelp.c
index 5d7bf8f016e..57a95fb8d8f 100644
--- a/dlls/toolhelp.dll16/toolhelp.c
+++ b/dlls/toolhelp.dll16/toolhelp.c
@@ -491,8 +491,8 @@ BOOL16 WINAPI TaskNext16( TASKENTRY *lpte )
     lpte->hTaskParent   = pTask->hParent;
     lpte->hInst         = pTask->hInstance;
     lpte->hModule       = pTask->hModule;
-    lpte->wSS           = SELECTOROF( pTask->teb->WOW32Reserved );
-    lpte->wSP           = OFFSETOF( pTask->teb->WOW32Reserved );
+    lpte->wSS           = SELECTOROF( pTask->teb->SystemReserved1[0] );
+    lpte->wSP           = OFFSETOF( pTask->teb->SystemReserved1[0] );
     lpte->wStackTop     = pInstData->stacktop;
     lpte->wStackMinimum = pInstData->stackmin;
     lpte->wStackBottom  = pInstData->stackbottom;
diff --git a/include/wine/winbase16.h b/include/wine/winbase16.h
index a3ff69b264d..71493395f3a 100644
--- a/include/wine/winbase16.h
+++ b/include/wine/winbase16.h
@@ -562,9 +562,9 @@ BOOL16      WINAPI WritePrivateProfileSection16(LPCSTR,LPCSTR,LPCSTR);
 BOOL16      WINAPI WritePrivateProfileStruct16(LPCSTR,LPCSTR,LPVOID,UINT16,LPCSTR);
 BOOL16      WINAPI WriteProfileSection16(LPCSTR,LPCSTR);
 
-#define CURRENT_STACK16 ((STACK16FRAME *)MapSL((SEGPTR)NtCurrentTeb()->WOW32Reserved))
+#define CURRENT_STACK16 ((STACK16FRAME *)MapSL((SEGPTR)NtCurrentTeb()->SystemReserved1[0]))
 #define CURRENT_DS      (CURRENT_STACK16->ds)
-#define CURRENT_SP      (((WORD *)&NtCurrentTeb()->WOW32Reserved)[0])
-#define CURRENT_SS      (((WORD *)&NtCurrentTeb()->WOW32Reserved)[1])
+#define CURRENT_SP      (((WORD *)NtCurrentTeb()->SystemReserved1)[0])
+#define CURRENT_SS      (((WORD *)NtCurrentTeb()->SystemReserved1)[1])
 
 #endif /* __WINE_WINE_WINBASE16_H */
diff --git a/tools/winebuild/relay.c b/tools/winebuild/relay.c
index 29d0a74c833..dc0960761a5 100644
--- a/tools/winebuild/relay.c
+++ b/tools/winebuild/relay.c
@@ -31,7 +31,7 @@
 #include "build.h"
 
 /* offset of the stack pointer relative to %fs:(0) */
-#define STACKOFFSET 0xc0  /* FIELD_OFFSET(TEB,WOW32Reserved) */
+#define STACKOFFSET 0x10c  /* FIELD_OFFSET(TEB,SystemReserved1) */
 
 /* fix this if the x86_thread_data structure is changed */
 #define GS_OFFSET  0x1d8  /* FIELD_OFFSET(TEB,SystemReserved2) + FIELD_OFFSET(struct x86_thread_data,gs) */