diff --git a/common/common_plotGERBER_functions.cpp b/common/common_plotGERBER_functions.cpp
index 6937351149..fbed464092 100644
--- a/common/common_plotGERBER_functions.cpp
+++ b/common/common_plotGERBER_functions.cpp
@@ -29,10 +29,13 @@ void GERBER_PLOTTER::SetViewport( const wxPoint& aOffset, double aIusPerDecimil,
     m_gerberUnitInch = false;    // Currently fixed, but could be an option
 
     // number of digits after the point (number of digits of the mantissa
-    // Be carefull: the coordinates are stored in an integer
-    // so 6 digits (inches) or 5 digits (mm) is the best value
-    // to avoid truncations and overflow
-    m_gerberUnitFmt = m_gerberUnitInch ? 6 : 5;
+    // Be carefull: the Gerber coordinates are stored in an integer
+    // so 6 digits (inches) or 5 digits (mm) is a good value
+    // To avoid overflow, 7 digits (inches) or 6 digits is a max.
+    // with lower values than 6 digits (inches) or 5 digits (mm),
+    // Creating self-intersecting polygons from non-intersecting polygons
+    // happen easily.
+    m_gerberUnitFmt = m_gerberUnitInch ? 7 : 6;
 
     m_IUsPerDecimil = aIusPerDecimil;
     iuPerDeviceUnit = pow( 10.0, m_gerberUnitFmt ) / ( aIusPerDecimil * 10000.0 );
diff --git a/pcbnew/class_board_design_settings.cpp b/pcbnew/class_board_design_settings.cpp
index f3596ced4b..844eb4211f 100644
--- a/pcbnew/class_board_design_settings.cpp
+++ b/pcbnew/class_board_design_settings.cpp
@@ -56,14 +56,14 @@ BOARD_DESIGN_SETTINGS::BOARD_DESIGN_SETTINGS() :
 {
     LSET    all_set = LSET().set();
 
-    m_enabledLayers = all_set;               // All layers enabled at first.
-                                                // SetCopperLayerCount() will adjust this.
+    m_enabledLayers = all_set;              // All layers enabled at first.
+                                            // SetCopperLayerCount() will adjust this.
     SetVisibleLayers( all_set );
 
     // set all but hidden text as visible.
     m_visibleElements = ~( 1 << MOD_TEXT_INVISIBLE );
 
-    SetCopperLayerCount( 2 );                   // Default design is a double sided board
+    SetCopperLayerCount( 2 );               // Default design is a double sided board
 
     // via type (VIA_BLIND_BURIED, VIA_THROUGH VIA_MICROVIA).
     m_CurrentViaType = VIA_THROUGH;
@@ -350,7 +350,9 @@ void BOARD_DESIGN_SETTINGS::SetCopperLayerCount( int aNewLayerCount )
     for( LAYER_NUM ii = LAYER_N_2; ii < aNewLayerCount - 1; ++ii )
         m_enabledLayers |= GetLayerSet( ii );
 #else
-    m_enabledLayers = LSET::AllCuMask( aNewLayerCount );
+    // Update only enabled copper layers mask
+    m_enabledLayers &= ~LSET::AllCuMask();
+    m_enabledLayers |= LSET::AllCuMask( aNewLayerCount );
 #endif
 }