diff --git a/xkb/xkb.c b/xkb/xkb.c
index f875a70c7..107284cff 100644
--- a/xkb/xkb.c
+++ b/xkb/xkb.c
@@ -5626,12 +5626,12 @@ _CheckSetGeom(XkbGeometryPtr geom, xkbSetGeometryReq * req, ClientPtr client)
         client->errorValue = _XkbErrCode3(0x01, 2, req->nColors);
         return BadValue;
     }
-    if (req->baseColorNdx > req->nColors) {
+    if (req->baseColorNdx >= req->nColors) {
         client->errorValue =
             _XkbErrCode3(0x03, req->nColors, req->baseColorNdx);
         return BadMatch;
     }
-    if (req->labelColorNdx > req->nColors) {
+    if (req->labelColorNdx >= req->nColors) {
         client->errorValue =
             _XkbErrCode3(0x03, req->nColors, req->labelColorNdx);
         return BadMatch;