diff --git a/aip/general/0009.md b/aip/general/0009.md
index 5140be056a..7a5bed46bc 100644
--- a/aip/general/0009.md
+++ b/aip/general/0009.md
@@ -47,7 +47,7 @@ API frontend server is often called an API proxy.
 away from each other. In some cases, they can be compiled into a single
 application binary and run inside a single process.
 
-#### API interface
+### API interface
 
 The element of an API specification IDL that groups API methods, such as a
 Protocol Buffers `service` definition. It is typically mapped to a similar high