diff --git a/example-file b/example-file.jrpc
similarity index 100%
rename from example-file
rename to example-file.jrpc
diff --git a/grammar.js b/grammar.js
index ec04996..9e6e79d 100644
--- a/grammar.js
+++ b/grammar.js
@@ -84,7 +84,12 @@ module.exports = grammar({
         ),
         ")",
       ),
-    function_argument: ($) => seq($.identifier, ":", $.type),
+    function_argument: ($) =>
+      seq(
+        field("argument_identifier", $.identifier),
+        ":",
+        field("argument_type", $.type),
+      ),
 
     pair: ($) =>
       seq(
diff --git a/src/grammar.json b/src/grammar.json
index 871aa0e..38d3806 100644
--- a/src/grammar.json
+++ b/src/grammar.json
@@ -510,16 +510,24 @@
       "type": "SEQ",
       "members": [
         {
-          "type": "SYMBOL",
-          "name": "identifier"
+          "type": "FIELD",
+          "name": "argument_identifier",
+          "content": {
+            "type": "SYMBOL",
+            "name": "identifier"
+          }
         },
         {
           "type": "STRING",
           "value": ":"
         },
         {
-          "type": "SYMBOL",
-          "name": "type"
+          "type": "FIELD",
+          "name": "argument_type",
+          "content": {
+            "type": "SYMBOL",
+            "name": "type"
+          }
         }
       ]
     },
diff --git a/src/node-types.json b/src/node-types.json
index 13829cf..7c5e2ec 100644
--- a/src/node-types.json
+++ b/src/node-types.json
@@ -203,20 +203,27 @@
   {
     "type": "function_argument",
     "named": true,
-    "fields": {},
-    "children": {
-      "multiple": true,
-      "required": true,
-      "types": [
-        {
-          "type": "identifier",
-          "named": true
-        },
-        {
-          "type": "type",
-          "named": true
-        }
-      ]
+    "fields": {
+      "argument_identifier": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "identifier",
+            "named": true
+          }
+        ]
+      },
+      "argument_type": {
+        "multiple": false,
+        "required": true,
+        "types": [
+          {
+            "type": "type",
+            "named": true
+          }
+        ]
+      }
     }
   },
   {
diff --git a/src/parser.c b/src/parser.c
index c8fe4a2..ba8c7d4 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -11,9 +11,9 @@
 #define ALIAS_COUNT 0
 #define TOKEN_COUNT 28
 #define EXTERNAL_TOKEN_COUNT 0
-#define FIELD_COUNT 5
+#define FIELD_COUNT 7
 #define MAX_ALIAS_SEQUENCE_LENGTH 5
-#define PRODUCTION_ID_COUNT 5
+#define PRODUCTION_ID_COUNT 6
 
 enum ts_symbol_identifiers {
   anon_sym_type = 1,
@@ -468,15 +468,19 @@ static const TSSymbolMetadata ts_symbol_metadata[] = {
 };
 
 enum ts_field_identifiers {
-  field_key = 1,
-  field_name = 2,
-  field_parameters = 3,
-  field_return_type = 4,
-  field_value = 5,
+  field_argument_identifier = 1,
+  field_argument_type = 2,
+  field_key = 3,
+  field_name = 4,
+  field_parameters = 5,
+  field_return_type = 6,
+  field_value = 7,
 };
 
 static const char * const ts_field_names[] = {
   [0] = NULL,
+  [field_argument_identifier] = "argument_identifier",
+  [field_argument_type] = "argument_type",
   [field_key] = "key",
   [field_name] = "name",
   [field_parameters] = "parameters",
@@ -488,7 +492,8 @@ static const TSFieldMapSlice ts_field_map_slices[PRODUCTION_ID_COUNT] = {
   [1] = {.index = 0, .length = 2},
   [2] = {.index = 2, .length = 2},
   [3] = {.index = 4, .length = 2},
-  [4] = {.index = 6, .length = 3},
+  [4] = {.index = 6, .length = 2},
+  [5] = {.index = 8, .length = 3},
 };
 
 static const TSFieldMapEntry ts_field_map_entries[] = {
@@ -502,6 +507,9 @@ static const TSFieldMapEntry ts_field_map_entries[] = {
     {field_name, 1},
     {field_parameters, 2},
   [6] =
+    {field_argument_identifier, 0},
+    {field_argument_type, 2},
+  [8] =
     {field_name, 0},
     {field_parameters, 1},
     {field_return_type, 3},
@@ -2363,8 +2371,8 @@ static const TSParseActionEntry ts_parse_actions[] = {
   [136] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_array_type, 2, 0, 0),
   [138] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_service_notification, 4, 0, 3),
   [140] = {.entry = {.count = 1, .reusable = false}}, REDUCE(sym_service_notification, 4, 0, 3),
-  [142] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_service_function, 5, 0, 4),
-  [144] = {.entry = {.count = 1, .reusable = false}}, REDUCE(sym_service_function, 5, 0, 4),
+  [142] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_service_function, 5, 0, 5),
+  [144] = {.entry = {.count = 1, .reusable = false}}, REDUCE(sym_service_function, 5, 0, 5),
   [146] = {.entry = {.count = 1, .reusable = true}}, SHIFT(66),
   [148] = {.entry = {.count = 1, .reusable = true}}, SHIFT(83),
   [150] = {.entry = {.count = 1, .reusable = true}}, SHIFT(56),
@@ -2406,7 +2414,7 @@ static const TSParseActionEntry ts_parse_actions[] = {
   [225] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_enum_value_assignment, 3, 0, 0),
   [227] = {.entry = {.count = 1, .reusable = true}}, SHIFT(11),
   [229] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_enum_value, 1, 0, 0),
-  [231] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_function_argument, 3, 0, 0),
+  [231] = {.entry = {.count = 1, .reusable = true}}, REDUCE(sym_function_argument, 3, 0, 4),
   [233] = {.entry = {.count = 1, .reusable = true}}, SHIFT(46),
   [235] = {.entry = {.count = 1, .reusable = true}}, SHIFT(54),
   [237] = {.entry = {.count = 1, .reusable = true}}, SHIFT(29),