diff --git a/eeschema/files-io.cpp b/eeschema/files-io.cpp
index 8cb5a6f9f4..cc5ffdb348 100644
--- a/eeschema/files-io.cpp
+++ b/eeschema/files-io.cpp
@@ -338,7 +338,18 @@ bool SCH_EDIT_FRAME::OpenProjectFiles( const std::vector<wxString>& aFileSet, in
 
         SetScreen( m_CurrentSheet->LastScreen() );
 
-        GetScreen()->ClrModify();
+        // It's possible the schematic parser fixed errors due to bugs so warn the user
+        // that the schematic has been fixed (modified).
+        SCH_SHEET_LIST sheetList( g_RootSheet );
+
+        if( sheetList.IsModified() )
+        {
+            DisplayInfoMessage( this,
+                                _( "An error was found when loading the schematic that has "
+                                   "been automatically fixed.  Please save the schematic to "
+                                   "repair the broken file or it may not be usable with other "
+                                   "versions of KiCad." ) );
+        }
 
         UpdateFileHistory( fullFileName );
 
diff --git a/eeschema/getpart.cpp b/eeschema/getpart.cpp
index ec5dff5307..151e0026c4 100644
--- a/eeschema/getpart.cpp
+++ b/eeschema/getpart.cpp
@@ -166,7 +166,7 @@ SCH_BASE_FRAME::COMPONENT_SELECTION SCH_BASE_FRAME::SelectComponentFromLibrary(
     if( alias == nullptr )      // Dialog closed by OK button, but no symbol selected
         return COMPONENT_SELECTION();
 
-    if( alias->GetPart()->IsMulti() && sel.Unit == 0 )
+    if( sel.Unit == 0 )
         sel.Unit = 1;
 
     sel.Fields = dlg.GetFields();
diff --git a/eeschema/sch_legacy_plugin.cpp b/eeschema/sch_legacy_plugin.cpp
index 12df024556..765a41c063 100644
--- a/eeschema/sch_legacy_plugin.cpp
+++ b/eeschema/sch_legacy_plugin.cpp
@@ -1336,7 +1336,20 @@ SCH_COMPONENT* SCH_LEGACY_PLUGIN::loadComponent( FILE_LINE_READER& aReader )
         }
         else if( strCompare( "U", line, &line ) )
         {
-            component->SetUnit( parseInt( aReader, line, &line ) );
+            // This fixes a potentially buggy files caused by unit being set to zero which
+            // causes netlist issues.  See https://bugs.launchpad.net/kicad/+bug/1677282.
+            int unit = parseInt( aReader, line, &line );
+
+            if( unit == 0 )
+            {
+                unit = 1;
+
+                // Set the file as modified so the user can be warned.
+                if( m_rootSheet && m_rootSheet->GetScreen() )
+                    m_rootSheet->GetScreen()->SetModify();
+            }
+
+            component->SetUnit( unit );
             component->SetConvert( parseInt( aReader, line, &line ) );
             component->SetTimeStamp( parseHex( aReader, line, &line ) );
         }