diff --git a/vlib/v/ast/table.v b/vlib/v/ast/table.v
index fdb4470b1c..a2440c4668 100644
--- a/vlib/v/ast/table.v
+++ b/vlib/v/ast/table.v
@@ -69,6 +69,8 @@ pub fn (mut t Table) free() {
 	}
 }
 
+pub const invalid_type_idx = -1
+
 pub type FnPanicHandler = fn (&Table, string)
 
 fn default_table_panic_handler(t &Table, message string) {
@@ -685,8 +687,8 @@ pub fn (t &Table) find_sym_and_type_idx(name string) (&TypeSymbol, int) {
 }
 
 pub const invalid_type_symbol = &TypeSymbol{
-	idx: -1
-	parent_idx: -1
+	idx: invalid_type_idx
+	parent_idx: invalid_type_idx
 	language: .v
 	mod: 'builtin'
 	kind: .placeholder
@@ -786,7 +788,7 @@ fn (mut t Table) rewrite_already_registered_symbol(typ TypeSymbol, existing_idx
 		}
 		return existing_idx
 	}
-	return -1
+	return ast.invalid_type_idx
 }
 
 [inline]
diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index 352b4e3725..994b65c03b 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -697,7 +697,8 @@ pub fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool)
 			node.pos)
 		return func.return_type
 	}
-	if func.return_type == ast.void_type && func.is_conditional && func.ctdefine_idx != -1 {
+	if func.return_type == ast.void_type && func.is_conditional
+		&& func.ctdefine_idx != ast.invalid_type_idx {
 		node.should_be_skipped = c.evaluate_once_comptime_if_attribute(mut func.attrs[func.ctdefine_idx])
 	}
 	// dont check number of args for JS functions since arguments are not required
@@ -1203,7 +1204,8 @@ pub fn (mut c Checker) method_call(mut node ast.CallExpr) ast.Type {
 			&& method.language == .v && method.no_body {
 			c.error('cannot call a method that does not have a body', node.pos)
 		}
-		if method.return_type == ast.void_type && method.is_conditional && method.ctdefine_idx != -1 {
+		if method.return_type == ast.void_type && method.is_conditional
+			&& method.ctdefine_idx != ast.invalid_type_idx {
 			node.should_be_skipped = c.evaluate_once_comptime_if_attribute(mut method.attrs[method.ctdefine_idx])
 		}
 		c.check_expected_arg_count(mut node, method) or { return method.return_type }
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index 0adf77053c..8a09e9e20c 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -402,7 +402,7 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 			receiver_type: rec.typ
 			//
 			attrs: p.attrs
-			is_conditional: conditional_ctdefine_idx != -1
+			is_conditional: conditional_ctdefine_idx != ast.invalid_type_idx
 			ctdefine_idx: conditional_ctdefine_idx
 			//
 			no_body: no_body
@@ -451,7 +451,7 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 			is_method: false
 			//
 			attrs: p.attrs
-			is_conditional: conditional_ctdefine_idx != -1
+			is_conditional: conditional_ctdefine_idx != ast.invalid_type_idx
 			ctdefine_idx: conditional_ctdefine_idx
 			//
 			no_body: no_body
@@ -506,7 +506,7 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 		is_markused: is_markused
 		//
 		attrs: p.attrs
-		is_conditional: conditional_ctdefine_idx != -1
+		is_conditional: conditional_ctdefine_idx != ast.invalid_type_idx
 		ctdefine_idx: conditional_ctdefine_idx
 		//
 		receiver: ast.StructField{
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index 3fcfe4815a..434082de31 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -3614,7 +3614,7 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 			}
 			is_public: is_pub
 		})
-		if typ == -1 {
+		if typ == ast.invalid_type_idx {
 			p.error_with_pos('cannot register sum type `$name`, another type with this name exists',
 				name_pos)
 			return ast.SumTypeDecl{}
@@ -3655,7 +3655,7 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 		is_public: is_pub
 	})
 	type_end_pos := p.prev_tok.pos()
-	if idx == -1 {
+	if idx == ast.invalid_type_idx {
 		p.error_with_pos('cannot register alias `$name`, another type with this name exists',
 			name_pos)
 		return ast.AliasTypeDecl{}