diff --git a/.gitmodules b/.gitmodules
index 58e995d..b9c9a33 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "source/prjxray"]
 	path = source/prjxray
 	url = ../prjxray
+[submodule "source/prjtrellis"]
+	path = source/prjtrellis
+	url = ../prjtrellis
diff --git a/source/index.rst b/source/index.rst
index d84c8a3..163155f 100644
--- a/source/index.rst
+++ b/source/index.rst
@@ -8,3 +8,4 @@ SymbiFlow documentation
    introduction
    fasm-specification
    prjxray/docs/index
+   prjtrellis/docs/index
diff --git a/source/prjtrellis b/source/prjtrellis
new file mode 160000
index 0000000..7848ab8
--- /dev/null
+++ b/source/prjtrellis
@@ -0,0 +1 @@
+Subproject commit 7848ab8db85194cb822bc27af5b50a6fe2db55c6