diff --git a/dlls/ntdll/tests/info.c b/dlls/ntdll/tests/info.c
index cf3f7b9f6f2..eaf2f1a45b7 100644
--- a/dlls/ntdll/tests/info.c
+++ b/dlls/ntdll/tests/info.c
@@ -2346,6 +2346,7 @@ static void test_affinity(void)
     DWORD_PTR proc_affinity, thread_affinity;
     THREAD_BASIC_INFORMATION tbi;
     SYSTEM_INFO si;
+    ULONG dummy;
 
     GetSystemInfo(&si);
     status = pNtQueryInformationProcess( GetCurrentProcess(), ProcessBasicInformation, &pbi, sizeof(pbi), NULL );
@@ -2450,6 +2451,32 @@ static void test_affinity(void)
     ok( status == STATUS_SUCCESS, "Expected STATUS_SUCCESS, got %08x\n", status);
     ok( tbi.AffinityMask == (1 << si.dwNumberOfProcessors) - 1,
         "Unexpected thread affinity\n" );
+
+    dummy = 0;
+    status = pNtSetInformationThread( GetCurrentThread(), ThreadHideFromDebugger, &dummy, sizeof(ULONG) );
+    ok( status == STATUS_INFO_LENGTH_MISMATCH, "Expected STATUS_INFO_LENGTH_MISMATCH, got %08x\n", status );
+    dummy = 0;
+    status = pNtSetInformationThread( GetCurrentThread(), ThreadHideFromDebugger, &dummy, 1 );
+    ok( status == STATUS_INFO_LENGTH_MISMATCH, "Expected STATUS_INFO_LENGTH_MISMATCH, got %08x\n", status );
+    status = pNtSetInformationThread( (HANDLE)0xdeadbeef, ThreadHideFromDebugger, NULL, 0 );
+    ok( status == STATUS_INVALID_HANDLE, "Expected STATUS_INVALID_HANDLE, got %08x\n", status );
+    status = pNtSetInformationThread( GetCurrentThread(), ThreadHideFromDebugger, NULL, 0 );
+    ok( status == STATUS_SUCCESS, "Expected STATUS_SUCCESS, got %08x\n", status );
+    dummy = 0;
+    status = NtQueryInformationThread( GetCurrentThread(), ThreadHideFromDebugger, &dummy, sizeof(ULONG), NULL );
+    if (status == STATUS_INVALID_INFO_CLASS)
+        win_skip("ThreadHideFromDebugger not available\n");
+    else
+    {
+        ok( status == STATUS_INFO_LENGTH_MISMATCH, "Expected STATUS_INFO_LENGTH_MISMATCH, got %08x\n", status );
+        dummy = 0;
+        status = NtQueryInformationThread( (HANDLE)0xdeadbeef, ThreadHideFromDebugger, &dummy, sizeof(ULONG), NULL );
+        ok( status == STATUS_INFO_LENGTH_MISMATCH, "Expected STATUS_INFO_LENGTH_MISMATCH, got %08x\n", status );
+        dummy = 0;
+        status = NtQueryInformationThread( GetCurrentThread(), ThreadHideFromDebugger, &dummy, 1, NULL );
+        ok( status == STATUS_SUCCESS, "Expected STATUS_SUCCESS, got %08x\n", status );
+        if (status == STATUS_SUCCESS) ok( dummy == 1, "Expected dummy == 1, got %08x\n", dummy );
+    }
 }
 
 static void test_NtGetCurrentProcessorNumber(void)
diff --git a/dlls/ntdll/unix/thread.c b/dlls/ntdll/unix/thread.c
index d26e0a98cac..2e2e5a3882d 100644
--- a/dlls/ntdll/unix/thread.c
+++ b/dlls/ntdll/unix/thread.c
@@ -831,6 +831,8 @@ NTSTATUS WINAPI NtQueryInformationThread( HANDLE handle, THREADINFOCLASS class,
 {
     NTSTATUS status;
 
+    TRACE("(%p,%d,%p,%x,%p)\n", handle, class, data, length, ret_len);
+
     switch (class)
     {
     case ThreadBasicInformation:
@@ -1063,6 +1065,14 @@ NTSTATUS WINAPI NtQueryInformationThread( HANDLE handle, THREADINFOCLASS class,
 #endif
     }
 
+    case ThreadHideFromDebugger:
+        if (length != sizeof(BOOLEAN)) return STATUS_INFO_LENGTH_MISMATCH;
+        if (!data) return STATUS_ACCESS_VIOLATION;
+        if (handle != GetCurrentThread()) return STATUS_ACCESS_DENIED;
+        *(BOOLEAN*)data = TRUE;
+        if (ret_len) *ret_len = sizeof(BOOLEAN);
+        return STATUS_SUCCESS;
+
     case ThreadPriority:
     case ThreadBasePriority:
     case ThreadImpersonationToken:
@@ -1088,6 +1098,8 @@ NTSTATUS WINAPI NtSetInformationThread( HANDLE handle, THREADINFOCLASS class,
 {
     NTSTATUS status;
 
+    TRACE("(%p,%d,%p,%x)\n", handle, class, data, length);
+
     switch (class)
     {
     case ThreadZeroTlsCell:
@@ -1152,6 +1164,8 @@ NTSTATUS WINAPI NtSetInformationThread( HANDLE handle, THREADINFOCLASS class,
     }
 
     case ThreadHideFromDebugger:
+        if (length) return STATUS_INFO_LENGTH_MISMATCH;
+        if (handle != GetCurrentThread()) return STATUS_INVALID_HANDLE;
         /* pretend the call succeeded to satisfy some code protectors */
         return STATUS_SUCCESS;