diff --git a/src/StdMeshers/StdMeshers_Prism_3D.cxx b/src/StdMeshers/StdMeshers_Prism_3D.cxx
index 0b9605e59..8b72f7b9b 100644
--- a/src/StdMeshers/StdMeshers_Prism_3D.cxx
+++ b/src/StdMeshers/StdMeshers_Prism_3D.cxx
@@ -2195,8 +2195,10 @@ bool StdMeshers_PrismAsBlock::Init(SMESH_MesherHelper*         helper,
     {
       if ( len2edgeMap.size() != nbEdges )
         RETURN_BAD_RESULT("Uniqueness of edge lengths not assured");
-      map< double, int >::reverse_iterator maxLen_i = len2edgeMap.rbegin();
-      map< double, int >::reverse_iterator midLen_i = ++len2edgeMap.rbegin();
+
+      multimap< double, int >::reverse_iterator maxLen_i = len2edgeMap.rbegin();
+      multimap< double, int >::reverse_iterator midLen_i = ++len2edgeMap.rbegin();
+
       double maxLen = maxLen_i->first;
       double midLen = ( len2edgeMap.size() == 1 ) ? 0 : midLen_i->first;
       switch ( nbEdges ) {