diff --git a/.gitmodules b/.gitmodules
index 10ea0bbf9675..9f66f4694653 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -5,7 +5,7 @@
 [submodule "external/mono"]
 	path = external/mono
 	url = ../../mono/mono.git
-	branch = 2017-04
+	branch = d15-3
 [submodule "external/fsharp"]
 	path = external/fsharp
 	url = ../../fsharp/fsharp.git