diff --git a/src/server/services/wms/qgswmsrendercontext.cpp b/src/server/services/wms/qgswmsrendercontext.cpp
index 79372cda728e..bfef86762d56 100644
--- a/src/server/services/wms/qgswmsrendercontext.cpp
+++ b/src/server/services/wms/qgswmsrendercontext.cpp
@@ -366,7 +366,8 @@ void QgsWmsRenderContext::searchLayersToRender()
 
   if ( mFlags & AddQueryLayers )
   {
-    for ( const QString &layer : flattenedQueryLayers() )
+    const auto constLayers { flattenedQueryLayers() };
+    for ( const QString &layer : constLayers )
     {
       if ( mNicknameLayers.contains( layer )
            && !mLayersToRender.contains( mNicknameLayers[layer] ) )
diff --git a/src/server/services/wms/qgswmsrendercontext.h b/src/server/services/wms/qgswmsrendercontext.h
index bdf6327beacb..cb132fca5f61 100644
--- a/src/server/services/wms/qgswmsrendercontext.h
+++ b/src/server/services/wms/qgswmsrendercontext.h
@@ -194,7 +194,7 @@ namespace QgsWms
 #endif
 
       /**
-       * Returns a map having layer group names as keys and a list of layer instances as values.
+       * Returns a map having layer group names as keys and a list of layers as values.
        * \since QGIS 3.8
        */
       QMap<QString, QList<QgsMapLayer *> > layerGroups() const;