diff --git a/libs/sdk-py/langgraph_sdk/sse.py b/libs/sdk-py/langgraph_sdk/sse.py
index b87788387..8b019e4a6 100644
--- a/libs/sdk-py/langgraph_sdk/sse.py
+++ b/libs/sdk-py/langgraph_sdk/sse.py
@@ -42,7 +42,7 @@ class BytesLineDecoder:
 
         if len(lines) == 1 and not trailing_newline:
             # No new lines, buffer the input and continue.
-            self.buffer.append(lines[0])
+            self.buffer.write(lines[0])
             return []
 
         if self.buffer:
diff --git a/libs/sdk-py/pyproject.toml b/libs/sdk-py/pyproject.toml
index c9e0401da..735954803 100644
--- a/libs/sdk-py/pyproject.toml
+++ b/libs/sdk-py/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "langgraph-sdk"
-version = "0.1.37"
+version = "0.1.38"
 description = "SDK for interacting with LangGraph API"
 authors = []
 license = "MIT"