diff --git a/eeschema/files-io.cpp b/eeschema/files-io.cpp
index 00e6f4fc3f..00fe5ace07 100644
--- a/eeschema/files-io.cpp
+++ b/eeschema/files-io.cpp
@@ -109,6 +109,10 @@ bool SCH_EDIT_FRAME::SaveEEFile( SCH_SHEET* aSheet, bool aSaveUnderNewName )
     if( !IsWritable( schematicFileName ) )
         return false;
 
+    // This is a new schematic file so make sure it has a unique ID.
+    if( aSaveUnderNewName )
+        screen->AssignNewUuid();
+
     wxFileName tempFile( schematicFileName );
     tempFile.SetName( wxT( "." ) + tempFile.GetName() );
     tempFile.SetExt( tempFile.GetExt() + wxT( "$" ) );
@@ -853,7 +857,22 @@ bool SCH_EDIT_FRAME::SaveProject()
     for( SCH_SHEET_PATH& sheetPath : Schematic().GetSheets() )
     {
         SCH_SHEET* sheet = sheetPath.Last();
-        sheets.emplace_back( std::make_pair( sheet->m_Uuid, sheet->GetName() ) );
+
+        wxCHECK2( sheet, continue );
+
+        // Use the schematic UUID for the root sheet.
+        if( sheet->IsRootSheet() )
+        {
+            screen = sheet->GetScreen();
+
+            wxCHECK2( screen, continue );
+
+            sheets.emplace_back( std::make_pair( screen->GetUuid(), sheet->GetName() ) );
+        }
+        else
+        {
+            sheets.emplace_back( std::make_pair( sheet->m_Uuid, sheet->GetName() ) );
+        }
     }
 
     if( !Prj().IsNullProject() )
diff --git a/eeschema/sch_file_versions.h b/eeschema/sch_file_versions.h
index d02d0959b3..411cdb71a5 100644
--- a/eeschema/sch_file_versions.h
+++ b/eeschema/sch_file_versions.h
@@ -1,7 +1,7 @@
 /*
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
- * Copyright (C) 2020 CERN
+ * Copyright (C) 2020-2021 CERN
  *
  * @author Wayne Stambaugh <stambaughw@gmail.com>
  *
@@ -26,7 +26,6 @@
  *
  * @note Comment out the last version and add the new version as a date time stamp in the
  *       YYYYMMDD format.  Comment the changes to the file format for historical purposes.
- *
  */
 
 /**
@@ -60,4 +59,5 @@
 //#define SEXPR_SCHEMATIC_FILE_VERSION 20201015  // Add sheet instance properties.
 //#define SEXPR_SCHEMATIC_FILE_VERSION 20210123  // Rename "unconnected" pintype to "no_connect".
 //#define SEXPR_SCHEMATIC_FILE_VERSION 20210125  // R/W uuids for pins, labels, wires, etc.
-#define SEXPR_SCHEMATIC_FILE_VERSION 20210126    // Fix bug with writing pin uuids.
+//#define SEXPR_SCHEMATIC_FILE_VERSION 20210126  // Fix bug with writing pin uuids.
+#define SEXPR_SCHEMATIC_FILE_VERSION 20210406    // Add schematic level uuids.
diff --git a/eeschema/sch_plugins/kicad/sch_sexpr_parser.cpp b/eeschema/sch_plugins/kicad/sch_sexpr_parser.cpp
index 8ec33244b8..53e92e1709 100644
--- a/eeschema/sch_plugins/kicad/sch_sexpr_parser.cpp
+++ b/eeschema/sch_plugins/kicad/sch_sexpr_parser.cpp
@@ -2046,6 +2046,12 @@ void SCH_SEXPR_PARSER::ParseSchematic( SCH_SHEET* aSheet, bool aIsCopyableOnly,
 
         switch( token )
         {
+        case T_uuid:
+            NeedSYMBOL();
+            screen->m_uuid = KIID( FromUTF8() );
+            NeedRIGHT();
+            break;
+
         case T_paper:
         {
             if( aIsCopyableOnly )
diff --git a/eeschema/sch_plugins/kicad/sch_sexpr_plugin.cpp b/eeschema/sch_plugins/kicad/sch_sexpr_plugin.cpp
index efc5fed865..b8d7d2420f 100644
--- a/eeschema/sch_plugins/kicad/sch_sexpr_plugin.cpp
+++ b/eeschema/sch_plugins/kicad/sch_sexpr_plugin.cpp
@@ -587,6 +587,8 @@ void SCH_SEXPR_PLUGIN::Format( SCH_SHEET* aSheet )
     m_out->Print( 0, "(kicad_sch (version %d) (generator eeschema)\n\n",
                   SEXPR_SCHEMATIC_FILE_VERSION );
 
+    m_out->Print( 1, "(uuid %s)\n\n", TO_UTF8( screen->m_uuid.AsString() ) );
+
     screen->GetPageSettings().Format( m_out, 1, 0 );
     m_out->Print( 0, "\n" );
     screen->GetTitleBlock().Format( m_out, 1, 0 );
diff --git a/eeschema/sch_screen.h b/eeschema/sch_screen.h
index 026a31899f..47e2b0caac 100644
--- a/eeschema/sch_screen.h
+++ b/eeschema/sch_screen.h
@@ -37,6 +37,7 @@
 #include <base_screen.h>
 #include <eda_item.h>
 #include <core/typeinfo.h>
+#include <kiid.h>
 #include <kiway_holder.h>
 #include <layers_id_colors_and_visibility.h>
 #include <marker_base.h>
@@ -457,6 +458,10 @@ public:
         return m_sheetInstances;
     }
 
+    const KIID& GetUuid() const { return m_uuid; }
+
+    void AssignNewUuid() { m_uuid = KIID(); }
+
 #if defined(DEBUG)
     void Show( int nestLevel, std::ostream& os ) const override;
 #endif
@@ -521,6 +526,14 @@ private:
      */
     std::vector<SYMBOL_INSTANCE_REFERENCE> m_symbolInstances;
     std::vector<SCH_SHEET_INSTANCE> m_sheetInstances;
+
+    /**
+     * A unique identifier for each schematic file.
+     *
+     * As of right now, this only has meaning for the root schematic.  In the future, it may
+     * be useful to detect unexpected hierarchy changes.
+     */
+    KIID m_uuid;
 };