diff --git a/litellm/llms/bedrock/chat/mantle/transformation.py b/litellm/llms/bedrock/chat/mantle/transformation.py
index d84e077c37b..e1d1ccf6155 100644
--- a/litellm/llms/bedrock/chat/mantle/transformation.py
+++ b/litellm/llms/bedrock/chat/mantle/transformation.py
@@ -70,7 +70,7 @@ class AmazonMantleConfig(AmazonAnthropicClaudeConfig):
         )
         project_id = litellm_params.get("aws_bedrock_project_id")
         if project_id:
-            headers["anthropic-workspace"] = project_id
+            headers["anthropic-workspace-id"] = project_id
         return headers
 
     def transform_request(