diff --git a/internal/compiler/analyzer/main_pkg.go b/internal/compiler/analyzer/main_pkg.go
index 69a0d14c..f867bde5 100644
--- a/internal/compiler/analyzer/main_pkg.go
+++ b/internal/compiler/analyzer/main_pkg.go
@@ -11,6 +11,7 @@ var (
 	ErrMainEntityNotFound       = errors.New("entity main is not found")
 	ErrMainEntityIsNotComponent = errors.New("main entity is not a component")
 	ErrMainEntityExported       = errors.New("main entity is exported")
+	ErrMainPkgExports           = errors.New("main pkg must not have exported entities")
 )
 
 func (a Analyzer) mainSpecificPkgValidation(pkg src.Package, pkgs map[string]src.Package) error {
@@ -31,5 +32,14 @@ func (a Analyzer) mainSpecificPkgValidation(pkg src.Package, pkgs map[string]src
 		return fmt.Errorf("analyze main component: %w", err)
 	}
 
+	if err := pkg.Entities(func(entity src.Entity, entityName, fileName string) error { // FIXME will conflict with general validation
+		if entity.Exported {
+			return fmt.Errorf("%w: file %v, entity %v", ErrMainPkgExports, fileName, entityName)
+		}
+		return nil
+	}); err != nil {
+		return err
+	}
+
 	return nil
 }
diff --git a/internal/compiler/src/src.go b/internal/compiler/src/src.go
index 3dba88ab..9978218d 100644
--- a/internal/compiler/src/src.go
+++ b/internal/compiler/src/src.go
@@ -40,6 +40,17 @@ func (p Package) Entity(name string) (Entity, bool) {
 	return Entity{}, false
 }
 
+func (p Package) Entities(f func(entity Entity, entityName string, fileName string) error) error {
+	for fileName, file := range p {
+		for entityName, entity := range file.Entities {
+			if err := f(entity, entityName, fileName); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
 type File struct {
 	Imports  map[string]string
 	Entities map[string]Entity