diff --git a/common/eda_draw_frame.cpp b/common/eda_draw_frame.cpp
index 143134816b..30fa8d4535 100644
--- a/common/eda_draw_frame.cpp
+++ b/common/eda_draw_frame.cpp
@@ -241,7 +241,8 @@ void EDA_DRAW_FRAME::OnUpdateSelectGrid( wxUpdateUIEvent& aEvent )
 
     int idx = config()->m_Window.grid.last_size_idx;
 
-    if( idx >= 0 && idx < m_gridSelectBox->GetCount() && idx != m_gridSelectBox->GetSelection() )
+    if( idx >= 0 && idx < int( m_gridSelectBox->GetCount() )
+            && idx != m_gridSelectBox->GetSelection() )
         m_gridSelectBox->SetSelection( idx );
 }
 
@@ -261,14 +262,14 @@ void EDA_DRAW_FRAME::OnSelectGrid( wxCommandEvent& event )
 
     int idx = m_gridSelectBox->GetCurrentSelection();
 
-    if( idx == m_gridSelectBox->GetCount() - 2 )
+    if( idx == int( m_gridSelectBox->GetCount() ) - 2 )
     {
         // wxWidgets will check the separator, which we don't want.
         // Re-check the current grid.
         wxUpdateUIEvent dummy;
         OnUpdateSelectGrid( dummy );
     }
-    else if( idx == m_gridSelectBox->GetCount() - 1 )
+    else if( idx == int( m_gridSelectBox->GetCount() ) - 1 )
     {
         // wxWidgets will check the Grid Settings... entry, which we don't want.
         // Re-check the current grid.
diff --git a/common/tool/common_tools.cpp b/common/tool/common_tools.cpp
index b316452735..dabf9be4f0 100644
--- a/common/tool/common_tools.cpp
+++ b/common/tool/common_tools.cpp
@@ -2,6 +2,7 @@
  * This program source code file is part of KiCad, a free EDA CAD application.
  *
  * Copyright (C) 2014-2016 CERN
+ * Copyright (C) 2020 KiCad Developers, see AUTHORS.txt for contributors.
  * @author Maciej Suminski <maciej.suminski@cern.ch>
  *
  * This program is free software; you can redistribute it and/or
@@ -355,7 +356,7 @@ int COMMON_TOOLS::GridNext( const TOOL_EVENT& aEvent )
 {
     int& currentGrid = m_toolMgr->GetSettings()->m_Window.grid.last_size_idx;
 
-    if( currentGrid + 1 < m_grids.size() )
+    if( currentGrid + 1 < int( m_grids.size() ) )
         currentGrid++;
 
     return OnGridChanged();
diff --git a/common/tool/grid_menu.cpp b/common/tool/grid_menu.cpp
index a6e9a95ab0..79d2917f43 100644
--- a/common/tool/grid_menu.cpp
+++ b/common/tool/grid_menu.cpp
@@ -63,7 +63,7 @@ OPT_TOOL_EVENT GRID_MENU::eventHandler( const wxMenuEvent& aEvent )
 void GRID_MENU::update()
 {
     APP_SETTINGS_BASE* settings = m_parent->config();
-    int                current = settings->m_Window.grid.last_size_idx;
+    unsigned int       current = settings->m_Window.grid.last_size_idx;
     wxArrayString      gridsList;
 
     BuildChoiceList( &gridsList, settings, m_parent->GetUserUnits() != EDA_UNITS::INCHES );
diff --git a/eeschema/dialogs/dialog_set_grid.cpp b/eeschema/dialogs/dialog_set_grid.cpp
index 32bbb8c1f6..373ee595d3 100644
--- a/eeschema/dialogs/dialog_set_grid.cpp
+++ b/eeschema/dialogs/dialog_set_grid.cpp
@@ -60,7 +60,7 @@ bool DIALOG_SET_GRID::TransferDataToWindow()
     for( const wxString& grid : grids )
         m_choiceGridSize->Append( grid );
 
-    if( idx >= 0 && idx < m_choiceGridSize->GetCount() )
+    if( idx >= 0 && idx < int( m_choiceGridSize->GetCount() ) )
         m_choiceGridSize->SetSelection( idx );
 
     return true;