diff --git a/nanobot/agent/context.py b/nanobot/agent/context.py
index 876d43d..b3de8da 100644
--- a/nanobot/agent/context.py
+++ b/nanobot/agent/context.py
@@ -235,7 +235,7 @@ To recall past events, grep {workspace_path}/memory/HISTORY.md"""
             msg["tool_calls"] = tool_calls
 
         # Include reasoning content when provided (required by some thinking models)
-        if reasoning_content:
+        if reasoning_content is not None:
             msg["reasoning_content"] = reasoning_content
 
         messages.append(msg)