diff --git a/include/libeval_compiler/libeval_compiler.h b/include/libeval_compiler/libeval_compiler.h
index ea0576386d..134028671d 100644
--- a/include/libeval_compiler/libeval_compiler.h
+++ b/include/libeval_compiler/libeval_compiler.h
@@ -178,8 +178,8 @@ public:
 class VALUE
 {
 public:
-    VALUE():
-        m_type(VT_UNDEFINED),
+    VALUE() :
+        m_type( VT_UNDEFINED ),
         m_valueDbl( 0 ),
         m_stringIsWildcard( false )
     {};
@@ -197,17 +197,20 @@ public:
         m_stringIsWildcard( false )
     {};
 
-    double AsDouble() const
+    virtual ~VALUE()
+    {};
+
+    virtual double AsDouble() const
     {
         return m_valueDbl;
     }
 
-    const wxString& AsString() const
+    virtual const wxString& AsString() const
     {
         return m_valueStr;
     }
 
-    bool EqualTo( const VALUE* b ) const;
+    virtual bool EqualTo( const VALUE* b ) const;
 
     VAR_TYPE_T GetType() const { return m_type; };
 
diff --git a/include/property.h b/include/property.h
index cfa1f72196..c51f1bb1da 100644
--- a/include/property.h
+++ b/include/property.h
@@ -522,7 +522,6 @@ public:
 
     ENUM_MAP& Map( T aValue, const wxString& aName )
     {
-        wxASSERT_MSG( m_choices.Index( aName ) == wxNOT_FOUND, "Redefined string for a value in ENUM_MAP" );
         m_choices.Add( aName, static_cast<int>( aValue ) );
         m_reverseMap[ aName ] = aValue;
         return *this;
diff --git a/pcbnew/drc/drc_rule_parser.cpp b/pcbnew/drc/drc_rule_parser.cpp
index ca669d23c8..5daf1ccc27 100644
--- a/pcbnew/drc/drc_rule_parser.cpp
+++ b/pcbnew/drc/drc_rule_parser.cpp
@@ -499,6 +499,7 @@ LSET DRC_RULES_PARSER::parseLayer()
         {
             reportError( wxString::Format( _( "Unrecognized layer '%s'." ),
                                            layerName ) );
+            retVal.set( UNDEFINED_LAYER );
         }
     }
 
diff --git a/pcbnew/pcb_edit_frame.cpp b/pcbnew/pcb_edit_frame.cpp
index 6af2368c20..2a2d29df83 100644
--- a/pcbnew/pcb_edit_frame.cpp
+++ b/pcbnew/pcb_edit_frame.cpp
@@ -1203,7 +1203,12 @@ void PCB_EDIT_FRAME::UpdateUserInterface()
     layerEnum.Undefined( UNDEFINED_LAYER );
 
     for( LSEQ seq = LSET::AllLayersMask().Seq(); seq; ++seq )
+    {
+        // Canonical name
+        layerEnum.Map( *seq, LSET::Name( *seq ) );
+        // User name
         layerEnum.Map( *seq, GetBoard()->GetLayerName( *seq ) );
+    }
 
     // Sync visibility with canvas
     KIGFX::VIEW* view = GetCanvas()->GetView();
diff --git a/pcbnew/pcb_expr_evaluator.cpp b/pcbnew/pcb_expr_evaluator.cpp
index 0f23cf4ef7..9eb6712e19 100644
--- a/pcbnew/pcb_expr_evaluator.cpp
+++ b/pcbnew/pcb_expr_evaluator.cpp
@@ -340,9 +340,9 @@ PCB_EXPR_BUILTIN_FUNCTIONS::PCB_EXPR_BUILTIN_FUNCTIONS()
 
 
 void PCB_EXPR_BUILTIN_FUNCTIONS::RegisterAllFunctions()
-                        {
+{
     m_funcs.clear();
-                            registerFunc( "existsOnLayer('x')", existsOnLayer );
+    RegisterFunc( "existsOnLayer('x')", existsOnLayer );
     RegisterFunc( "isPlated()", isPlated );
     RegisterFunc( "insideCourtyard('x')", insideCourtyard );
     RegisterFunc( "insideArea('x')", insideArea );
@@ -364,8 +364,43 @@ BOARD_ITEM* PCB_EXPR_VAR_REF::GetObject( LIBEVAL::CONTEXT* aCtx ) const
 }
 
 
+class PCB_LAYER_VALUE : public LIBEVAL::VALUE
+{
+public:
+    PCB_LAYER_VALUE( PCB_LAYER_ID aLayer ) :
+        LIBEVAL::VALUE( double( aLayer ) )
+    {};
+
+    virtual bool EqualTo( const VALUE* b ) const override
+    {
+        // For boards with user-defined layer names there will be 2 entries for each layer
+        // in the ENUM_MAP: one for the canonical layer name and one for the user layer name.
+        // We need to check against both.
+
+        wxPGChoices& layerMap = ENUM_MAP<PCB_LAYER_ID>::Instance().Choices();
+        PCB_LAYER_ID layerId = ToLAYER_ID( (int) AsDouble() );
+
+        for( unsigned ii = 0; ii < layerMap.GetCount(); ++ii )
+        {
+            wxPGChoiceEntry& entry = layerMap[ii];
+
+            if( entry.GetValue() == layerId && entry.GetText().Matches( b->AsString() ) )
+                return true;
+        }
+
+        return false;
+    }
+};
+
+
 LIBEVAL::VALUE PCB_EXPR_VAR_REF::GetValue( LIBEVAL::CONTEXT* aCtx )
 {
+    if( m_itemIndex == 2 )
+    {
+        PCB_EXPR_CONTEXT* context = static_cast<PCB_EXPR_CONTEXT*>( aCtx );
+        return PCB_LAYER_VALUE( context->GetLayer() );
+    }
+
     BOARD_ITEM* item  = const_cast<BOARD_ITEM*>( GetObject( aCtx ) );
     auto        it = m_matchingTypes.find( TYPE_HASH( *item ) );
 
@@ -413,7 +448,7 @@ std::unique_ptr<LIBEVAL::VAR_REF> PCB_EXPR_UCODE::CreateVarRef( const wxString&
                                                                 const wxString& aField )
 {
     PROPERTY_MANAGER& propMgr = PROPERTY_MANAGER::Instance();
-    std::unique_ptr<PCB_EXPR_VAR_REF> vref;;
+    std::unique_ptr<PCB_EXPR_VAR_REF> vref;
 
     if( aVar == "A" )
     {
@@ -423,6 +458,10 @@ std::unique_ptr<LIBEVAL::VAR_REF> PCB_EXPR_UCODE::CreateVarRef( const wxString&
     {
         vref.reset( new PCB_EXPR_VAR_REF( 1 ) );
     }
+    else if( aVar == "L" )
+    {
+        vref.reset( new PCB_EXPR_VAR_REF( 2 ) );
+    }
     else
     {
         return nullptr;