diff --git a/src/main/java/eu/dnetlib/dhp/schema/solr/PersonTopic.java b/src/main/java/eu/dnetlib/dhp/schema/solr/PersonTopic.java
index 2115e34..2f19f96 100644
--- a/src/main/java/eu/dnetlib/dhp/schema/solr/PersonTopic.java
+++ b/src/main/java/eu/dnetlib/dhp/schema/solr/PersonTopic.java
@@ -11,11 +11,11 @@ public class PersonTopic implements Serializable {
 
     private String schema;
 
-    private Year fromYear;
+    private String fromYear;
 
-    private Year toYear;
+    private String toYear;
 
-    public static PersonTopic newInstance(String value, String schema, Year fromYear, Year toYear) {
+    public static PersonTopic newInstance(String value, String schema, String fromYear, String toYear) {
         final PersonTopic personTopic = new PersonTopic();
         personTopic.setValue(value);
         personTopic.setSchema(schema);
@@ -43,19 +43,19 @@ public class PersonTopic implements Serializable {
         this.schema = schema;
     }
 
-    public Year getFromYear() {
+    public String getFromYear() {
         return fromYear;
     }
 
-    public void setFromYear(Year fromYear) {
+    public void setFromYear(String fromYear) {
         this.fromYear = fromYear;
     }
 
-    public Year getToYear() {
+    public String getToYear() {
         return toYear;
     }
 
-    public void setToYear(Year toYear) {
+    public void setToYear(String toYear) {
         this.toYear = toYear;
     }
 }