diff --git a/jps/model-serialization/src/org/jetbrains/jps/model/serialization/JpsModelSerializerExtension.java b/jps/model-serialization/src/org/jetbrains/jps/model/serialization/JpsModelSerializerExtension.java
index 78c389822ea6..554fbb53449a 100644
--- a/jps/model-serialization/src/org/jetbrains/jps/model/serialization/JpsModelSerializerExtension.java
+++ b/jps/model-serialization/src/org/jetbrains/jps/model/serialization/JpsModelSerializerExtension.java
@@ -66,7 +66,7 @@ public abstract class JpsModelSerializerExtension {
   }
 
   @NotNull
-  public List<JpsLibraryPropertiesSerializer<?>> getLibraryPropertiesLoaders() {
+  public List<? extends JpsLibraryPropertiesSerializer<?>> getLibraryPropertiesLoaders() {
     return Collections.emptyList();
   }