diff --git a/core/trino-spi/src/main/java/io/trino/spi/connector/ConnectorSplitSource.java b/core/trino-spi/src/main/java/io/trino/spi/connector/ConnectorSplitSource.java
index 87a964099cb2..04bbba0cde6b 100644
--- a/core/trino-spi/src/main/java/io/trino/spi/connector/ConnectorSplitSource.java
+++ b/core/trino-spi/src/main/java/io/trino/spi/connector/ConnectorSplitSource.java
@@ -20,6 +20,11 @@
 
 import static java.util.Objects.requireNonNull;
 
+/**
+ * Source of splits to be processed.
+ * <p>
+ * Thread-safety: the implementations are not required to be thread-safe.
+ */
 public interface ConnectorSplitSource
         extends Closeable
 {