diff --git a/LUA_GdbGetSurf.cpp b/LUA_GdbGetSurf.cpp
index 2bdd842..f680f9d 100644
--- a/LUA_GdbGetSurf.cpp
+++ b/LUA_GdbGetSurf.cpp
@@ -629,7 +629,7 @@ LuaSurfTmFacetMinAreaRectangle( lua_State* L)
 static int
 LuaSurfTmFacetElevationInBBox( lua_State* L)
 {
-  // 2 o 3 parametri : Id, nFacet [, nRefId]
+  // 3 o 4 parametri : Id, nFacet, b3Box [, nRefId]
    int nId ;
    LuaCheckParam( L, 1, nId)
    int nFacet ;