diff --git a/src/main/java/org/qortal/repository/hsqldb/HSQLDBRepository.java b/src/main/java/org/qortal/repository/hsqldb/HSQLDBRepository.java
index 09c6a6d4..4d8e5043 100644
--- a/src/main/java/org/qortal/repository/hsqldb/HSQLDBRepository.java
+++ b/src/main/java/org/qortal/repository/hsqldb/HSQLDBRepository.java
@@ -55,7 +55,7 @@ public class HSQLDBRepository implements Repository {
 
 	private static final Logger LOGGER = LogManager.getLogger(HSQLDBRepository.class);
 
-	private static final Object CHECKPOINT_LOCK = new Object();
+	public static final Object CHECKPOINT_LOCK = new Object();
 
 	// "serialization failure"
 	private static final Integer DEADLOCK_ERROR_CODE = Integer.valueOf(-4861);
@@ -703,8 +703,11 @@ public class HSQLDBRepository implements Repository {
 	private ResultSet checkedExecuteResultSet(PreparedStatement preparedStatement, Object... objects) throws SQLException {
 		bindStatementParams(preparedStatement, objects);
 
-		if (!preparedStatement.execute())
-			throw new SQLException("Fetching from database produced no results");
+		// synchronize to block new executions if checkpointing in progress
+		synchronized (CHECKPOINT_LOCK) {
+			if (!preparedStatement.execute())
+				throw new SQLException("Fetching from database produced no results");
+		}
 
 		ResultSet resultSet = preparedStatement.getResultSet();
 		if (resultSet == null)
@@ -1056,4 +1059,4 @@ public class HSQLDBRepository implements Repository {
 		return DEADLOCK_ERROR_CODE.equals(e.getErrorCode());
 	}
 
-}
\ No newline at end of file
+}
diff --git a/src/main/java/org/qortal/repository/hsqldb/HSQLDBSaver.java b/src/main/java/org/qortal/repository/hsqldb/HSQLDBSaver.java
index c1b6ee9b..acf24c54 100644
--- a/src/main/java/org/qortal/repository/hsqldb/HSQLDBSaver.java
+++ b/src/main/java/org/qortal/repository/hsqldb/HSQLDBSaver.java
@@ -61,13 +61,15 @@ public class HSQLDBSaver {
 	public boolean execute(HSQLDBRepository repository) throws SQLException {
 		String sql = this.formatInsertWithPlaceholders();
 
-		try {
-			PreparedStatement preparedStatement = repository.prepareStatement(sql);
-			this.bindValues(preparedStatement);
+		synchronized (HSQLDBRepository.CHECKPOINT_LOCK) {
+			try {
+				PreparedStatement preparedStatement = repository.prepareStatement(sql);
+				this.bindValues(preparedStatement);
 
-			return preparedStatement.execute();
-		} catch (SQLException e) {
-			throw repository.examineException(e);
+				return preparedStatement.execute();
+			} catch (SQLException e) {
+				throw repository.examineException(e);
+			}
 		}
 	}