diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index 2f6961d7dc..6a5ec1bacb 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -156,7 +156,7 @@ digraph_setlist({digraphlist})	Boolean	register multiple |digraph|s
 echoraw({expr})			none	output {expr} as-is
 empty({expr})			Number	|TRUE| if {expr} is empty
 environ()			Dict	return environment variables
-err_teapot()			Number	produce error 418
+err_teapot([{expr}])		none	give E418, or E503 if {expr} is |TRUE|
 escape({string}, {chars})	String	escape {chars} in {string} with '\'
 eval({string})			any	evaluate {string} into its value
 eventhandler()			Number	|TRUE| if inside an event handler
diff --git a/src/evalfunc.c b/src/evalfunc.c
index ab6606f76f..ef0414c689 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -3936,7 +3936,7 @@ f_err_teapot(typval_T *argvars, typval_T *rettv UNUSED)
 	if (argvars[0].v_type == VAR_STRING)
 	{
 	    char_u *s = tv_get_string_strict(&argvars[0]);
-	    if (s == NULL || *skipwhite(s) == NUL)
+	    if (*skipwhite(s) == NUL)
 		return;
 	}
 
diff --git a/src/version.c b/src/version.c
index 0661b279ba..b9e584d205 100644
--- a/src/version.c
+++ b/src/version.c
@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1727,
 /**/
     1726,
 /**/