diff --git a/mapwmslayer.c b/mapwmslayer.c
index 4e1bcb93c7..0c68f250b9 100755
--- a/mapwmslayer.c
+++ b/mapwmslayer.c
@@ -734,8 +734,8 @@ msBuildWMSLayerURL(mapObj *map, layerObj *lp, int nRequestType,
 
         msRectIntersect( &bbox, &layer_rect );
 
-        bbox_width = ceil((bbox.maxx - bbox.minx) / cellsize);
-        bbox_height = ceil((bbox.maxy - bbox.miny) / cellsize);
+        bbox_width = round((bbox.maxx - bbox.minx) / cellsize);
+        bbox_height = round((bbox.maxy - bbox.miny) / cellsize);
 
         /* Force going through the resampler if we're going to receive a clipped BBOX (#4931) */
         if(msLayerGetProcessingKey(lp, "RESAMPLE") == NULL) {
diff --git a/msautotest/gdal/expected/wmsclient_3543.png b/msautotest/gdal/expected/wmsclient_3543.png
index 407f15a590..45a3942da0 100644
Binary files a/msautotest/gdal/expected/wmsclient_3543.png and b/msautotest/gdal/expected/wmsclient_3543.png differ