diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index 6c198d061e..ea276459dc 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -1370,14 +1370,16 @@ void call_user_func(ufunc_T *fp, int argcount, typval_T *argvars, typval_T *rett
 }
 
 /// There are two kinds of function names:
-/// 1. ordinary names, function defined with :function
-/// 2. numbered functions and lambdas
+/// 1. ordinary names, function defined with :function;
+///    can start with "<SNR>123_" literally or with K_SPECIAL.
+/// 2. Numbered functions and lambdas: "<lambda>123"
 /// For the first we only count the name stored in func_hashtab as a reference,
 /// using function() does not count as a reference, because the function is
 /// looked up by name.
 static bool func_name_refcount(const char *name)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE
 {
-  return isdigit((uint8_t)(*name)) || *name == '<';
+  return isdigit((uint8_t)(*name)) || (name[0] == '<' && name[1] == 'l');
 }
 
 /// Check the argument count for user function "fp".