diff --git a/README.md b/README.md
index 5b01603..be26f56 100644
--- a/README.md
+++ b/README.md
@@ -146,6 +146,12 @@
 your value of CFLAGS doesn't override the content provided by cmake (depending
 on the build mode as seen above), it's merely prepended to it.
 
+#### Mbed TLS as a subproject
+
+Mbed TLS, like Mbed Crypto, supports being built as a CMake subproject. One can
+use `add_subdirectory()` from a parent CMake project to include Mbed TLS as a
+subproject.
+
 ### Microsoft Visual Studio
 
 The build files for Microsoft Visual Studio are generated for Visual Studio 2010.