diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index e782061..37aba38 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -161,6 +161,7 @@
   call assert_equal(256, str2nr("1'0000'0000", 2, 1))
   call assert_equal(262144, str2nr("1'000'000", 8, 1))
   call assert_equal(1000000, str2nr("1'000'000", 10, 1))
+  call assert_equal(1000, str2nr("1'000''000", 10, 1))
   call assert_equal(65536, str2nr("1'00'00", 16, 1))
 
   call assert_equal(0, str2nr('0x10'))