diff --git a/src/testdir/test_substitute.vim b/src/testdir/test_substitute.vim
index c056fa9..7e7ccff 100644
--- a/src/testdir/test_substitute.vim
+++ b/src/testdir/test_substitute.vim
@@ -995,7 +995,7 @@
     ~
     s/
   endfunc
-  silent!  s/\%')/\=Repl()
+  silent! s/\%')/\=Repl()
 
   delfunc Repl
   bwipe!
@@ -1359,4 +1359,14 @@
   bw!
 endfunc
 
+" This should be done last to reveal a memory leak when vim_regsub_both() is
+" called to evaluate an expression but it is not used in a second call.
+func Test_z_substitute_expr_leak()
+  func SubExpr()
+    ~n
+  endfunc
+  silent! s/\%')/\=SubExpr()
+  delfunc SubExpr
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab