diff --git a/src/main/java/org/qortal/repository/hsqldb/HSQLDBDatabaseUpdates.java b/src/main/java/org/qortal/repository/hsqldb/HSQLDBDatabaseUpdates.java
index e29d6b44..a0cc4b85 100644
--- a/src/main/java/org/qortal/repository/hsqldb/HSQLDBDatabaseUpdates.java
+++ b/src/main/java/org/qortal/repository/hsqldb/HSQLDBDatabaseUpdates.java
@@ -695,7 +695,7 @@ public class HSQLDBDatabaseUpdates {
 					stmt.execute("CHECKPOINT");
 					break;
 
-				case 30:
+				case 30: {
 					// Split AT state data off to new table for better performance/management.
 
 					if (!wasPristine && !"mem".equals(HSQLDBRepository.getDbPathname(connection.getMetaData().getURL()))) {
@@ -770,12 +770,42 @@ public class HSQLDBDatabaseUpdates {
 					stmt.execute("ALTER TABLE ATStatesNew RENAME TO ATStates");
 					stmt.execute("CHECKPOINT");
 					break;
+				}
 
-				case 31:
+				case 31: {
 					// AT sleep-until-message support
+					LOGGER.info("Altering AT table in repository - this might take a while... (approx. 20 seconds on high-spec)");
 					stmt.execute("ALTER TABLE ATs ADD sleep_until_message_timestamp BIGINT");
-					stmt.execute("ALTER TABLE ATStates ADD sleep_until_message_timestamp BIGINT");
+
+					// Create new AT-states table with new column
+					stmt.execute("CREATE TABLE ATStatesNew ("
+							+ "AT_address QortalAddress, height INTEGER NOT NULL, state_hash ATStateHash NOT NULL, "
+							+ "fees QortalAmount NOT NULL, is_initial BOOLEAN NOT NULL, sleep_until_message_timestamp BIGINT, "
+							+ "PRIMARY KEY (AT_address, height), "
+							+ "FOREIGN KEY (AT_address) REFERENCES ATs (AT_address) ON DELETE CASCADE)");
+					stmt.execute("SET TABLE ATStatesNew NEW SPACE");
+					stmt.execute("CHECKPOINT");
+
+					ResultSet resultSet = stmt.executeQuery("SELECT height FROM Blocks ORDER BY height DESC LIMIT 1");
+					final int blockchainHeight = resultSet.next() ? resultSet.getInt(1) : 0;
+					final int heightStep = 100;
+
+					LOGGER.info("Altering AT states table in repository - this might take a while... (approx. 3 mins on high-spec)");
+					for (int minHeight = 1; minHeight < blockchainHeight; minHeight += heightStep) {
+						stmt.execute("INSERT INTO ATStatesNew ("
+								+ "SELECT AT_address, height, state_hash, fees, is_initial, NULL "
+								+ "FROM ATStates "
+								+ "WHERE height BETWEEN " + minHeight + " AND " + (minHeight + heightStep - 1)
+								+ ")");
+						stmt.execute("COMMIT");
+					}
+					stmt.execute("CHECKPOINT");
+
+					stmt.execute("DROP TABLE ATStates");
+					stmt.execute("ALTER TABLE ATStatesNew RENAME TO ATStates");
+					stmt.execute("CHECKPOINT");
 					break;
+				}
 
 				default:
 					// nothing to do