diff --git a/devel/monotone/patches/patch-test_unit_tests_merge_3way_cc b/devel/monotone/patches/patch-test_unit_tests_merge_3way_cc
new file mode 100644
index 00000000000..a55988e8c89
--- /dev/null
+++ b/devel/monotone/patches/patch-test_unit_tests_merge_3way_cc
@@ -0,0 +1,12 @@
+$OpenBSD: patch-test_unit_tests_merge_3way_cc,v 1.1 2017/03/13 01:53:19 bluhm Exp $
+--- test/unit/tests/merge_3way.cc.orig	Sun May  4 11:15:25 2014
++++ test/unit/tests/merge_3way.cc	Mon Mar 13 01:40:08 2017
+@@ -17,6 +17,8 @@
+ #include "../randomfile.hh"
+ #include "../../../src/simplestring_xform.hh"
+ 
++#include <iostream>
++
+ using std::cerr;
+ using std::cout;
+ using std::stringstream;