diff --git a/src/testdir/test69.in b/src/testdir/test69.in
index 9558cb8..f18ee37 100644
--- a/src/testdir/test69.in
+++ b/src/testdir/test69.in
@@ -1,6 +1,7 @@
 Test for multi-byte text formatting.
 Also test, that 'mps' with multibyte chars works.
 And test "ra" on multi-byte characters.
+Also test byteidx() and byteidxcomp()
 
 STARTTEST
 :so mbyte.vim
@@ -154,6 +155,21 @@
 ａａb
 
 STARTTEST
+:let a = '.é.' " one char of two bytes
+:let b = '.é.' " normal e with composing char
+/^byteidx
+:put =string([byteidx(a, 0), byteidx(a, 1), byteidx(a, 2), byteidx(a, 3), byteidx(a, 4)])
+:put =string([byteidx(b, 0), byteidx(b, 1), byteidx(b, 2), byteidx(b, 3), byteidx(b, 4)])
+/^byteidxcomp
+:put =string([byteidxcomp(a, 0), byteidxcomp(a, 1), byteidxcomp(a, 2), byteidxcomp(a, 3), byteidxcomp(a, 4)])
+:let b = '.é.'
+:put =string([byteidxcomp(b, 0), byteidxcomp(b, 1), byteidxcomp(b, 2), byteidxcomp(b, 3), byteidxcomp(b, 4), byteidxcomp(b, 5)])
+ENDTEST
+
+byteidx
+byteidxcomp
+
+STARTTEST
 :g/^STARTTEST/.,/^ENDTEST/d
 :1;/^Results/,$wq! test.out
 ENDTEST
diff --git a/src/testdir/test69.ok b/src/testdir/test69.ok
index f742ee1..1ff82f2 100644
--- a/src/testdir/test69.ok
+++ b/src/testdir/test69.ok
@@ -149,3 +149,11 @@
 aaaa
 aaa
 
+
+byteidx
+[0, 1, 3, 4, -1]
+[0, 1, 4, 5, -1]
+byteidxcomp
+[0, 1, 3, 4, -1]
+[0, 1, 2, 4, 5, -1]
+