diff --git a/eeschema/dialogs/dialog_sim_settings.cpp b/eeschema/dialogs/dialog_sim_settings.cpp
index 8301c8329a..6fb55ddce8 100644
--- a/eeschema/dialogs/dialog_sim_settings.cpp
+++ b/eeschema/dialogs/dialog_sim_settings.cpp
@@ -365,17 +365,17 @@ int DIALOG_SIM_SETTINGS::ShowModal()
         { m_noiseRef, m_noiseRef->GetStringSelection() }
     };
 
-    for( auto c : cmbNet )
+    for( auto& c : cmbNet )
         c.first->Clear();
 
     for( const auto& net : m_circuitModel->GetNets() )
     {
-        for( auto c : cmbNet )
+        for( auto& c : cmbNet )
             c.first->Append( net );
     }
 
     // Try to restore the previous selection, if possible
-    for( auto c : cmbNet )
+    for( auto& c : cmbNet )
     {
         int idx = c.first->FindString( c.second );
 
diff --git a/eeschema/sim/sim_plot_panel.cpp b/eeschema/sim/sim_plot_panel.cpp
index 573532d5fd..ff58c367ef 100644
--- a/eeschema/sim/sim_plot_panel.cpp
+++ b/eeschema/sim/sim_plot_panel.cpp
@@ -638,7 +638,7 @@ void SIM_PLOT_PANEL::ResetScales()
     if( m_axis_y2 )
         m_axis_y2->ResetDataRange();
 
-    for( auto t : m_traces )
+    for( auto& t : m_traces )
         t.second->UpdateScales();
 }
 
diff --git a/eeschema/symbol_library_manager.cpp b/eeschema/symbol_library_manager.cpp
index 3f5775bc9c..e9d7f12030 100644
--- a/eeschema/symbol_library_manager.cpp
+++ b/eeschema/symbol_library_manager.cpp
@@ -1256,7 +1256,7 @@ bool SYMBOL_LIBRARY_MANAGER::LIB_BUFFER::HasDerivedSymbols( const wxString& aPar
 
 void SYMBOL_LIBRARY_MANAGER::LIB_BUFFER::GetRootSymbolNames( wxArrayString& aRootSymbolNames )
 {
-    for( auto entry : m_symbols )
+    for( auto& entry : m_symbols )
     {
         if( entry->GetSymbol()->IsAlias() )
             continue;
diff --git a/kicad/kicad_manager_frame.cpp b/kicad/kicad_manager_frame.cpp
index f7562c20c9..2effe01086 100644
--- a/kicad/kicad_manager_frame.cpp
+++ b/kicad/kicad_manager_frame.cpp
@@ -437,7 +437,7 @@ void KICAD_MANAGER_FRAME::DoWithAcceptedFiles()
     std::vector<std::string> gerberExts( GerberFileExtensions );
     gerberExts.push_back( DrillFileExtension );
 
-    for( auto fileName : m_AcceptedFiles )
+    for( const wxFileName& fileName : m_AcceptedFiles )
     {
         if( IsExtensionAccepted( fileName.GetExt(), gerberExts ) )
         {
diff --git a/pcbnew/router/pns_dragger.cpp b/pcbnew/router/pns_dragger.cpp
index 11d0ee161a..6f0b8cc67b 100644
--- a/pcbnew/router/pns_dragger.cpp
+++ b/pcbnew/router/pns_dragger.cpp
@@ -97,7 +97,7 @@ VVIA* DRAGGER::checkVirtualVia( const VECTOR2D& aP, SEGMENT* aSeg )
         return nullptr;
     }
 
-    for( auto lnk : jt->LinkList() )
+    for( auto& lnk : jt->LinkList() )
     {
         if( lnk.item->IsVirtual() && lnk.item->OfKind( ITEM::VIA_T ))
         {
diff --git a/pcbnew/router/router_tool.cpp b/pcbnew/router/router_tool.cpp
index 5fb36941b6..377fba7ee8 100644
--- a/pcbnew/router/router_tool.cpp
+++ b/pcbnew/router/router_tool.cpp
@@ -565,7 +565,7 @@ void ROUTER_TOOL::saveRouterDebugLog()
 
     const auto& events = logger->GetEvents();
 
-    for( auto evt : events)
+    for( const auto& evt : events)
     {
         fprintf( f, "event %d %d %d %s\n", evt.p.x, evt.p.y, evt.type,
                  static_cast<const char*>( evt.uuid.AsString().c_str() ) );
diff --git a/qa/unittests/eeschema/test_pin_numbers.cpp b/qa/unittests/eeschema/test_pin_numbers.cpp
index a0cbe095b7..1b93f7dff3 100644
--- a/qa/unittests/eeschema/test_pin_numbers.cpp
+++ b/qa/unittests/eeschema/test_pin_numbers.cpp
@@ -121,7 +121,7 @@ BOOST_AUTO_TEST_CASE( ComparePinNumbers )
 
     };
 
-    for( auto el : cases )
+    for( auto& el : cases )
     {
         int retval = PIN_NUMBERS::Compare( el.m_lhs, el.m_rhs );
         wxString msg;
diff --git a/qa/unittests/pcbnew/test_graphics_import_mgr.cpp b/qa/unittests/pcbnew/test_graphics_import_mgr.cpp
index 2f81749e0d..8cae0d1850 100644
--- a/qa/unittests/pcbnew/test_graphics_import_mgr.cpp
+++ b/qa/unittests/pcbnew/test_graphics_import_mgr.cpp
@@ -37,7 +37,7 @@ static bool pluginHandlesExt( const GRAPHICS_IMPORT_PLUGIN& aPlugin, const std::
 {
     const auto exts = aPlugin.GetFileExtensions();
 
-    for( auto ext : exts )
+    for( const auto& ext : exts )
     {
         std::regex ext_reg( ext );