diff --git a/reactos/subsystems/win32/win32k/eng/xlate.c b/reactos/subsystems/win32/win32k/eng/xlate.c
index 43aec9f91f7..eef2457da3d 100644
--- a/reactos/subsystems/win32/win32k/eng/xlate.c
+++ b/reactos/subsystems/win32/win32k/eng/xlate.c
@@ -158,6 +158,9 @@ IntEngCreateXlate(USHORT DestPalType, USHORT SourcePalType,
    ULONG DestRedMask = 0, DestGreenMask = 0, DestBlueMask = 0;
    ULONG i;
 
+   ASSERT(SourcePalType || PaletteSource);
+   ASSERT(DestPalType || PaletteDest);
+
    XlateGDI = EngAllocMem(0, sizeof(XLATEGDI), TAG_XLATEOBJ);
    if (XlateGDI == NULL)
    {