diff --git a/stage0/astgen.c b/stage0/astgen.c
index 8ad6115723..e9a02ca018 100644
--- a/stage0/astgen.c
+++ b/stage0/astgen.c
@@ -6587,7 +6587,7 @@ static uint32_t fnProtoExprInner(
     uint32_t return_type_rhs = proto_data.rhs;
 
     if (proto_tag == AST_NODE_FN_PROTO_SIMPLE) {
-        if (proto_data.lhs != 0) {
+        if (proto_data.lhs != NULL_NODE) {
             param_nodes_buf[0] = proto_data.lhs;
             param_nodes = param_nodes_buf;
             params_len = 1;
@@ -6595,7 +6595,7 @@ static uint32_t fnProtoExprInner(
     } else if (proto_tag == AST_NODE_FN_PROTO_ONE) {
         uint32_t extra_idx = proto_data.lhs;
         uint32_t param = tree->extra_data.arr[extra_idx];
-        if (param != 0) {
+        if (param != NULL_NODE) {
             param_nodes_buf[0] = param;
             param_nodes = param_nodes_buf;
             params_len = 1;
@@ -6628,7 +6628,10 @@ static uint32_t fnProtoExprInner(
     bool is_var_args = false;
 
     uint32_t fn_token = tree->nodes.main_tokens[node];
-    uint32_t lparen = fn_token + 1;
+    uint32_t after_fn_token = fn_token + 1;
+    uint32_t lparen = (tree->tokens.tags[after_fn_token] == TOKEN_IDENTIFIER)
+        ? after_fn_token + 1
+        : after_fn_token;
     uint32_t iter_tok_i = lparen + 1;
     bool iter_tok_flag = true;
     uint32_t iter_param_i = 0;