diff --git a/src/testdir/test_mapping.in b/src/testdir/test_mapping.in
index 55dac09..e257277 100644
--- a/src/testdir/test_mapping.in
+++ b/src/testdir/test_mapping.in
@@ -3,6 +3,7 @@
 STARTTEST
 :so small.vim
 :so mbyte.vim
+:set encoding=utf-8
 : " abbreviations with р (0x80) should work
 :inoreab чкпр   vim
 GAчкпр