diff --git a/src/testdir/test_source.vim b/src/testdir/test_source.vim
index 35d1453..5f45ab4 100644
--- a/src/testdir/test_source.vim
+++ b/src/testdir/test_source.vim
@@ -646,4 +646,13 @@
   %bw!
 endfunc
 
+func Test_source_buffer_long_line()
+  " This was reading past the end of the line.
+  new
+  norm300gr0
+  so
+  bwipe!
+endfunc
+
+
 " vim: shiftwidth=2 sts=2 expandtab