diff --git a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiCollectorPlugin.java b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiCollectorPlugin.java
index 67fd352a3..9918e4abe 100644
--- a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiCollectorPlugin.java
+++ b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiCollectorPlugin.java
@@ -21,6 +21,9 @@ import eu.dnetlib.dhp.collection.plugin.CollectorPlugin;
 
 public class OaiCollectorPlugin implements CollectorPlugin {
 
+	public static final String DATE_REGEX = "\\d{4}-\\d{2}-\\d{2}";
+	public static final String UTC_DATETIME_REGEX = "\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z";
+
 	private static final String FORMAT_PARAM = "format";
 	private static final String OAI_SET_PARAM = "set";
 	private static final Object OAI_FROM_DATE_PARAM = "fromDate";
@@ -62,11 +65,11 @@ public class OaiCollectorPlugin implements CollectorPlugin {
 			throw new CollectorException("Param 'mdFormat' is null or empty");
 		}
 
-		if (fromDate != null && !fromDate.matches("\\d{4}-\\d{2}-\\d{2}") && !fromDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z")) {
+		if (fromDate != null && !fromDate.matches(DATE_REGEX) && !fromDate.matches(UTC_DATETIME_REGEX)) {
 			throw new CollectorException("Invalid date (YYYY-MM-DD): " + fromDate);
 		}
 
-		if (untilDate != null && !untilDate.matches("\\d{4}-\\d{2}-\\d{2}") && !untilDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z")) {
+		if (untilDate != null && !untilDate.matches(DATE_REGEX) && !untilDate.matches(UTC_DATETIME_REGEX)) {
 			throw new CollectorException("Invalid date (YYYY-MM-DD): " + untilDate);
 		}
 
diff --git a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiIterator.java b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiIterator.java
index c044e02db..75dd746ea 100644
--- a/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiIterator.java
+++ b/dhp-workflows/dhp-aggregation/src/main/java/eu/dnetlib/dhp/collection/plugin/oai/OaiIterator.java
@@ -107,10 +107,12 @@ public class OaiIterator implements Iterator<String> {
 			if (set != null && !set.isEmpty()) {
 				url += "&set=" + URLEncoder.encode(set, "UTF-8");
 			}
-			if (fromDate != null && (fromDate.matches("\\d{4}-\\d{2}-\\d{2}") || fromDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z"))) {
+			if (fromDate != null && (fromDate.matches(OaiCollectorPlugin.DATE_REGEX)
+				|| fromDate.matches(OaiCollectorPlugin.UTC_DATETIME_REGEX))) {
 				url += "&from=" + URLEncoder.encode(fromDate, "UTF-8");
 			}
-			if (untilDate != null && (untilDate.matches("\\d{4}-\\d{2}-\\d{2}") || untilDate.matches("\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}Z"))) {
+			if (untilDate != null && (untilDate.matches(OaiCollectorPlugin.DATE_REGEX)
+				|| untilDate.matches(OaiCollectorPlugin.UTC_DATETIME_REGEX))) {
 				url += "&until=" + URLEncoder.encode(untilDate, "UTF-8");
 			}
 			log.info("Start harvesting using url: " + url);