diff --git a/src/evalfunc.c b/src/evalfunc.c
index 4f68845..3817352 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -6814,6 +6814,7 @@
 	return FALSE;
 
     found = tv_get_bool_chk(&newtv, &error);
+    clear_tv(&newtv);
 
     return error ? FALSE : found;
 }
@@ -6864,6 +6865,7 @@
 {
     listitem_T	*item;
     long	idx = 0;
+    int		found;
 
     if (l == NULL)
 	return -1;
@@ -6888,7 +6890,10 @@
 	set_vim_var_nr(VV_KEY, idx);
 	copy_tv(&item->li_tv, get_vim_var_tv(VV_VAL));
 
-	if (indexof_eval_expr(expr))
+	found = indexof_eval_expr(expr);
+	clear_tv(get_vim_var_tv(VV_VAL));
+
+	if (found)
 	    return idx;
     }
 
diff --git a/src/testdir/test_blob.vim b/src/testdir/test_blob.vim
index 46f2d61..46370c4 100644
--- a/src/testdir/test_blob.vim
+++ b/src/testdir/test_blob.vim
@@ -772,6 +772,7 @@
   call assert_equal(-1, indexof(b, {i, v -> v == 0x1}))
   call assert_equal(1, indexof(b, "v:val == 0xad"))
   call assert_equal(-1, indexof(b, "v:val == 0xff"))
+  call assert_equal(-1, indexof(b, {_, v -> "v == 0xad"}))
 
   call assert_equal(-1, indexof(0z, "v:val == 0x0"))
   call assert_equal(-1, indexof(test_null_blob(), "v:val == 0xde"))
diff --git a/src/testdir/test_listdict.vim b/src/testdir/test_listdict.vim
index 2c4e5c7..bba4e3e 100644
--- a/src/testdir/test_listdict.vim
+++ b/src/testdir/test_listdict.vim
@@ -1462,7 +1462,13 @@
   call assert_equal(-1, indexof(l, "v:val.n == 10", #{startidx: -4}))
   call assert_equal(0, indexof(l, "v:val.n == 10", test_null_dict()))
 
+  let s = ["a", "b", "c"]
+  call assert_equal(2, indexof(s, {_, v -> v == 'c'}))
+  call assert_equal(-1, indexof(s, {_, v -> v == 'd'}))
+  call assert_equal(-1, indexof(s, {_, v -> "v == 'd'"}))
+
   call assert_equal(-1, indexof([], {i, v -> v == 'a'}))
+  call assert_equal(-1, indexof([1, 2, 3], {_, v -> "v == 2"}))
   call assert_equal(-1, indexof(test_null_list(), {i, v -> v == 'a'}))
   call assert_equal(-1, indexof(l, test_null_string()))
   call assert_equal(-1, indexof(l, test_null_function()))
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index 244021c..55ede98 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -2074,10 +2074,36 @@
   var b = 0zdeadbeef
   indexof(b, "v:val == 0xef")->assert_equal(3)
 
-  def TestIdx(k: number, v: dict<any>): bool
+  def TestIdx1(k: number, v: dict<any>): bool
     return v.color == 'blue'
   enddef
-  indexof(l, TestIdx)->assert_equal(1)
+  indexof(l, TestIdx1)->assert_equal(1)
+
+  var lines =<< trim END
+    def TestIdx(v: dict<any>): bool
+      return v.color == 'blue'
+    enddef
+
+    indexof([{color: "red"}], TestIdx)
+  END
+  v9.CheckDefAndScriptFailure(lines, ['E176: Invalid number of arguments', 'E118: Too many arguments for function'])
+
+  lines =<< trim END
+    def TestIdx(k: number, v: dict<any>)
+    enddef
+
+    indexof([{color: "red"}], TestIdx)
+  END
+  v9.CheckDefAndScriptFailure(lines, ['E1013: Argument 2: type mismatch, expected func(?number, ?any): bool', 'E1031: Cannot use void value'])
+
+  lines =<< trim END
+    def TestIdx(k: number, v: dict<any>): string
+      return "abc"
+    enddef
+
+    indexof([{color: "red"}], TestIdx)
+  END
+  v9.CheckDefAndScriptFailure(lines, ['E1013: Argument 2: type mismatch, expected func(?number, ?any): bool', 'E1135: Using a String as a Bool'])
 enddef
 
 def Test_input()
diff --git a/src/version.c b/src/version.c
index f901eea..3b5193f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -736,6 +736,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    204,
+/**/
     203,
 /**/
     202,