diff --git a/dlls/kernel32/tests/thread.c b/dlls/kernel32/tests/thread.c
index 334bdf49277..5918a58e299 100644
--- a/dlls/kernel32/tests/thread.c
+++ b/dlls/kernel32/tests/thread.c
@@ -1325,10 +1325,12 @@ static DWORD WINAPI LS_ThreadProc(LPVOID p)
     ok(LS_index0 != LS_index1, "%s failed\n", LS_AllocFuncName);
 
     /* Both slots should be initialized to NULL */
+    SetLastError(0xdeadbeef);
     val = LS_GetValueFunc(LS_index0);
     ok(GetLastError() == ERROR_SUCCESS, "%s failed\n", LS_GetValueFuncName);
     ok(val == NULL, "Slot not initialized correctly\n");
 
+    SetLastError(0xdeadbeef);
     val = LS_GetValueFunc(LS_index1);
     ok(GetLastError() == ERROR_SUCCESS, "%s failed\n", LS_GetValueFuncName);
     ok(val == NULL, "Slot not initialized correctly\n");
@@ -1337,10 +1339,12 @@ static DWORD WINAPI LS_ThreadProc(LPVOID p)
 
   if (sync_threads_and_run_one(0, id))
   {
+    SetLastError(0xdeadbeef);
     val = LS_GetValueFunc(LS_index0);
     ok(GetLastError() == ERROR_SUCCESS, "%s failed\n", LS_GetValueFuncName);
     ok(val == NULL, "Slot not initialized correctly\n");
 
+    SetLastError(0xdeadbeef);
     val = LS_GetValueFunc(LS_index1);
     ok(GetLastError() == ERROR_SUCCESS, "%s failed\n", LS_GetValueFuncName);
     ok(val == NULL, "Slot not initialized correctly\n");
@@ -1351,10 +1355,12 @@ static DWORD WINAPI LS_ThreadProc(LPVOID p)
     ret = LS_SetValueFunc(LS_index1, (LPVOID) 2);
     ok(ret, "%s failed\n", LS_SetValueFuncName);
 
+    SetLastError(0xdeadbeef);
     val = LS_GetValueFunc(LS_index0);
     ok(GetLastError() == ERROR_SUCCESS, "%s failed\n", LS_GetValueFuncName);
     ok(val == (LPVOID) 1, "Slot not initialized correctly\n");
 
+    SetLastError(0xdeadbeef);
     val = LS_GetValueFunc(LS_index1);
     ok(GetLastError() == ERROR_SUCCESS, "%s failed\n", LS_GetValueFuncName);
     ok(val == (LPVOID) 2, "Slot not initialized correctly\n");