diff --git a/lang/mono5.20/files/patch-external_boringssl_CMakeLists.txt b/lang/mono5.20/files/patch-external_boringssl_CMakeLists.txt
new file mode 100644
index 000000000000..b9e3efb9e1b9
--- /dev/null
+++ b/lang/mono5.20/files/patch-external_boringssl_CMakeLists.txt
@@ -0,0 +1,8 @@
+--- external/boringssl/CMakeLists.txt.orig	2019-07-16 18:16:26 UTC
++++ external/boringssl/CMakeLists.txt
+@@ -1,4 +1,4 @@
+-cmake_minimum_required (VERSION 2.8.10)
++cmake_minimum_required (VERSION 3.5)
+ 
+ # Defer enabling C and CXX languages.
+ project (BoringSSL NONE)
diff --git a/lang/mono5.20/files/patch-mono_btls_CMakeLists.txt b/lang/mono5.20/files/patch-mono_btls_CMakeLists.txt
new file mode 100644
index 000000000000..c7ce65cca9d4
--- /dev/null
+++ b/lang/mono5.20/files/patch-mono_btls_CMakeLists.txt
@@ -0,0 +1,8 @@
+--- mono/btls/CMakeLists.txt.orig	2019-07-16 18:16:12 UTC
++++ mono/btls/CMakeLists.txt
+@@ -1,4 +1,4 @@
+-cmake_minimum_required (VERSION 2.8.10)
++cmake_minimum_required (VERSION 3.5)
+ 
+ project (mono-btls)
+