diff --git a/tools/grib_to_netcdf.c b/tools/grib_to_netcdf.c
index 3b2fdb3e7..e20b74213 100644
--- a/tools/grib_to_netcdf.c
+++ b/tools/grib_to_netcdf.c
@@ -1657,6 +1657,7 @@ static void cube_indexes(
         }
         indexes[i] = j;
     }
+    (void)index;
 }
 
 /*********************************/