diff --git a/docs/deployment/http.mdx b/docs/deployment/http.mdx
index 962c2e013..17ec9e825 100644
--- a/docs/deployment/http.mdx
+++ b/docs/deployment/http.mdx
@@ -344,13 +344,6 @@ Here's a quick example showing how to add MCP to an existing FastAPI application
 from fastapi import FastAPI
 from fastmcp import FastMCP
 
-# Your existing API
-api = FastAPI()
-
-@api.get("/api/status")
-def status():
-    return {"status": "ok"}
-
 # Create your MCP server
 mcp = FastMCP("API Tools")
 
@@ -359,14 +352,28 @@ def query_database(query: str) -> dict:
     """Run a database query"""
     return {"result": "data"}
 
+# Create the MCP ASGI app with path="/" since we'll mount at /mcp
+mcp_app = mcp.http_app(path="/")
+
+# Create FastAPI app with MCP lifespan (required for session management)
+api = FastAPI(lifespan=mcp_app.lifespan)
+
+@api.get("/api/status")
+def status():
+    return {"status": "ok"}
+
 # Mount MCP at /mcp
-api.mount("/mcp", mcp.http_app())
+api.mount("/mcp", mcp_app)
 
 # Run with: uvicorn app:api --host 0.0.0.0 --port 8000
 ```
 
 Your existing API remains at `http://localhost:8000/api` while MCP is available at `http://localhost:8000/mcp`.
 
+<Warning>
+Just like with Starlette, you **must** pass the lifespan from the MCP app to FastAPI. Without this, the session manager won't initialize properly and requests will fail.
+</Warning>
+
 ## Mounting Authenticated Servers
 
 <VersionBadge version="2.13.0" />
diff --git a/docs/integrations/fastapi.mdx b/docs/integrations/fastapi.mdx
index 2ce28336d..abdc1d0e7 100644
--- a/docs/integrations/fastapi.mdx
+++ b/docs/integrations/fastapi.mdx
@@ -390,14 +390,14 @@ def get_user(user_id: int):
 When mounting MCP servers, always pass the lifespan context:
 
 ```python
-# Correct - lifespan passed
-mcp_app = mcp.http_app(path='/mcp')
+# Correct - lifespan passed, path="/" since we mount at /mcp
+mcp_app = mcp.http_app(path="/")
 app = FastAPI(lifespan=mcp_app.lifespan)
-app.mount("/mcp", mcp_app)
+app.mount("/mcp", mcp_app)  # MCP endpoint at /mcp
 
 # Incorrect - missing lifespan
 app = FastAPI()
-app.mount("/mcp", mcp.http_app())  # Session manager won't initialize
+app.mount("/mcp", mcp.http_app(path="/"))  # Session manager won't initialize
 ```
 
 If you're mounting an authenticated MCP server under a path prefix, see [Mounting Authenticated Servers](/deployment/http#mounting-authenticated-servers) for important OAuth routing considerations.
@@ -427,7 +427,7 @@ async def app_lifespan(app: FastAPI):
 
 # Create MCP server
 mcp = FastMCP("Tools")
-mcp_app = mcp.http_app()
+mcp_app = mcp.http_app(path="/")
 
 # Combine both lifespans
 app = FastAPI(lifespan=combine_lifespans(app_lifespan, mcp_app.lifespan))