diff --git a/src/eval.c b/src/eval.c
index 4f56463..cc289b4 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -3259,7 +3259,7 @@
 	char_u *p = STRNCMP(arg, "<SNR>", 5) == 0 ? skipdigits(arg + 5) : arg;
 
 	if (to_name_end(p, TRUE) == parens)
-	    r = call_simple_func(arg, (int)(parens - arg), rettv);
+	    r = call_simple_func(arg, (size_t)(parens - arg), rettv);
     }
     return r;
 }
diff --git a/src/proto/userfunc.pro b/src/proto/userfunc.pro
index ce5d257..32dac66 100644
--- a/src/proto/userfunc.pro
+++ b/src/proto/userfunc.pro
@@ -39,7 +39,7 @@
 varnumber_T call_callback_retnr(callback_T *callback, int argcount, typval_T *argvars);
 void user_func_error(funcerror_T error, char_u *name, int found_var);
 int call_func(char_u *funcname, int len, typval_T *rettv, int argcount_in, typval_T *argvars_in, funcexe_T *funcexe);
-int call_simple_func(char_u *funcname, int len, typval_T *rettv);
+int call_simple_func(char_u *funcname, size_t len, typval_T *rettv);
 char_u *printable_func_name(ufunc_T *fp);
 char_u *trans_function_name(char_u **pp, int *is_global, int skip, int flags);
 char_u *trans_function_name_ext(char_u **pp, int *is_global, int skip, int flags, funcdict_T *fdp, partial_T **partial, type_T **type, ufunc_T **ufunc);
diff --git a/src/userfunc.c b/src/userfunc.c
index 1c58b01..9a82394 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -4058,7 +4058,7 @@
     int
 call_simple_func(
     char_u	*funcname,	// name of the function
-    int		len,		// length of "name" or -1 to use strlen()
+    size_t	len,		// length of "name"
     typval_T	*rettv)		// return value goes here
 {
     int		ret = FAIL;
diff --git a/src/version.c b/src/version.c
index 3ca6001..76b00a9 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    649,
+/**/
     648,
 /**/
     647,