diff --git a/src/plugins/streamers/lefdef/db_plugin/dbDEFImporter.cc b/src/plugins/streamers/lefdef/db_plugin/dbDEFImporter.cc
index 057402473..ea8fd7f76 100644
--- a/src/plugins/streamers/lefdef/db_plugin/dbDEFImporter.cc
+++ b/src/plugins/streamers/lefdef/db_plugin/dbDEFImporter.cc
@@ -999,15 +999,17 @@ DEFImporter::read_vias (db::Layout & /*layout*/, db::Cell & /*design*/, double s
 
         if (m_lef_importer.is_routing_layer (ln)) {
 
-          if (routing_layers.size () == 0) {
-            geo_based_vg->set_maskshift_layer (0, ln);
-          } else if (routing_layers.size () == 1) {
-            geo_based_vg->set_maskshift_layer (2, ln);
-          }
-
           if (seen_layers.find (ln) == seen_layers.end ()) {
+
+            if (routing_layers.size () == 0) {
+              geo_based_vg->set_maskshift_layer (0, ln);
+            } else if (routing_layers.size () == 1) {
+              geo_based_vg->set_maskshift_layer (2, ln);
+            }
+
             seen_layers.insert (ln);
             routing_layers.push_back (ln);
+
           }
 
         } else if (m_lef_importer.is_cut_layer (ln)) {
diff --git a/src/plugins/streamers/lefdef/db_plugin/dbLEFDEFImporter.cc b/src/plugins/streamers/lefdef/db_plugin/dbLEFDEFImporter.cc
index 08e3d1ea8..96086bc95 100644
--- a/src/plugins/streamers/lefdef/db_plugin/dbLEFDEFImporter.cc
+++ b/src/plugins/streamers/lefdef/db_plugin/dbLEFDEFImporter.cc
@@ -279,7 +279,7 @@ GeometryBasedLayoutGenerator::mask_for (const std::string &ln, unsigned int m, c
 
       if (m == 0 || ! nm) {
         m = mm;
-      } else if (m > 0) {
+      } else if (mm > 0) {
         m = (m + mm - 2) % nm->number_of_masks (ln) + 1;
       }
 
diff --git a/src/plugins/streamers/lefdef/db_plugin/dbLEFDEFImporter.h b/src/plugins/streamers/lefdef/db_plugin/dbLEFDEFImporter.h
index 4b9ca747d..94e34b3ca 100644
--- a/src/plugins/streamers/lefdef/db_plugin/dbLEFDEFImporter.h
+++ b/src/plugins/streamers/lefdef/db_plugin/dbLEFDEFImporter.h
@@ -942,7 +942,9 @@ public:
 
   void set_maskshift_layer (unsigned int l, const std::string &s)
   {
-    m_maskshift_layers.resize (l + 1, std::string ());
+    if (m_maskshift_layers.size () <= size_t (l)) {
+      m_maskshift_layers.resize (l + 1, std::string ());
+    }
     m_maskshift_layers[l] = s;
   }