Index: s57reader.cpp
===================================================================
--- s57reader.cpp   (revision 0000)
+++ s57reader.cpp   (working copy)
@@ -2635,16 +2635,30 @@
         /* If we don't have SG2D, check for SG3D */
         if( poDstSG2D == NULL )
         {
-            poSrcSG2D = poUpdate->FindField("SG3D");
             poDstSG2D = poTarget->FindField("SG3D");
+            if (poDstSG2D != NULL) {
+               poSrcSG2D = poUpdate->FindField("SG3D");
+            }
         }

-        if( (poSrcSG2D == NULL && nCCUI != 2) || poDstSG2D == NULL )
+        if( (poSrcSG2D == NULL && nCCUI != 2) || (poDstSG2D == NULL && nCCUI != 1) )
         {
             CPLAssert( FALSE );
             return FALSE;
         }

+        if (poDstSG2D == NULL) {
+          poTarget->AddField(poTarget->GetModule()->FindFieldDefn("SG2D"));
+          poDstSG2D = poTarget->FindField("SG2D");
+          if (poDstSG2D == NULL) {
+            CPLAssert( FALSE );
+            return FALSE;
+          }
+
+          // Delete null default data that was created
+          poTarget->SetFieldRaw( poDstSG2D, 0, NULL, 0 );
+        }
+
         nCoordSize = poDstSG2D->GetFieldDefn()->GetFixedWidth();

         if( nCCUI == 1 ) /* INSERT */