diff --git a/langfuse/_client/environment_variables.py b/langfuse/_client/environment_variables.py
index 7667ba213..b868b1e24 100644
--- a/langfuse/_client/environment_variables.py
+++ b/langfuse/_client/environment_variables.py
@@ -83,7 +83,7 @@
 """
 .. envvar:: LANGFUSE_FLUSH_INTERVAL
 
-Max delay until a new ingestion batch is sent to the API.
+Max delay in seconds until a new ingestion batch is sent to the API.
 **Default value:** ``1``
 """
 
diff --git a/langfuse/_client/span_processor.py b/langfuse/_client/span_processor.py
index 0e0a92f98..13451b6de 100644
--- a/langfuse/_client/span_processor.py
+++ b/langfuse/_client/span_processor.py
@@ -93,7 +93,9 @@ def __init__(
             span_exporter=langfuse_span_exporter,
             export_timeout_millis=timeout * 1_000 if timeout else None,
             max_export_batch_size=flush_at,
-            schedule_delay_millis=flush_interval,
+            schedule_delay_millis=flush_interval * 1_000
+            if flush_interval is not None
+            else None,
         )
 
     def on_end(self, span: ReadableSpan) -> None: