diff --git a/lib/filterx/expr-function.c b/lib/filterx/expr-function.c
index 013bcf7e07..89da1b6c8f 100644
--- a/lib/filterx/expr-function.c
+++ b/lib/filterx/expr-function.c
@@ -88,49 +88,43 @@ _get_arg_object(FilterXSimpleFunction *self, guint64 index)
   return filterx_expr_eval(expr);
 }
 
-static GPtrArray *
-_simple_function_eval_args(FilterXSimpleFunction *self)
+static gboolean
+_simple_function_eval_args(FilterXSimpleFunction *self, FilterXObject **args, gsize *args_len)
 {
-  GPtrArray *res = g_ptr_array_new_full(self->args->len, (GDestroyNotify) filterx_object_unref);
-
-  for (guint64 i = 0; i < self->args->len; i++)
+  gsize n = *args_len;
+  for (gsize i = 0; i < n; i++)
     {
-      FilterXObject *obj = _get_arg_object(self, i);
-      if (obj == NULL)
-        goto error;
-
-      g_ptr_array_add(res, obj);
+      if ((args[i] = _get_arg_object(self, i)) == NULL)
+        {
+          *args_len = i;
+          return FALSE;
+        }
     }
+  *args_len = n;
+  return TRUE;
+}
 
-  return res;
-
-error:
-  g_ptr_array_free(res, TRUE);
-  return NULL;
+static void
+_simple_function_free_args(FilterXObject *args[], gsize args_len)
+{
+  for (gsize i = 0; i < args_len; i++)
+    filterx_object_unref(args[i]);
 }
 
 static FilterXObject *
 _simple_eval(FilterXExpr *s)
 {
   FilterXSimpleFunction *self = (FilterXSimpleFunction *) s;
+  gsize args_len = self->args->len;
+  FilterXObject *args[self->args->len];
+  FilterXObject *res = NULL;
 
-  GPtrArray *args = NULL;
-
-  if (self->args->len)
+  if (_simple_function_eval_args(self, args, &args_len))
     {
-      args = _simple_function_eval_args(self);
-      if (!args)
-        return NULL;
+      res = self->function_proto(s, args, args_len);
     }
 
-  FilterXSimpleFunctionProto f = self->function_proto;
-
-  g_assert(f != NULL);
-  FilterXObject *res = f(s, args);
-
-  if (args != NULL)
-    g_ptr_array_free(args, TRUE);
-
+  _simple_function_free_args(args, args_len);
   return res;
 }
 
diff --git a/lib/filterx/expr-function.h b/lib/filterx/expr-function.h
index 0c1085f2a1..513f0a86f5 100644
--- a/lib/filterx/expr-function.h
+++ b/lib/filterx/expr-function.h
@@ -33,7 +33,7 @@
 #include "generic-number.h"
 #include "plugin.h"
 
-typedef FilterXObject *(*FilterXSimpleFunctionProto)(FilterXExpr *s, GPtrArray *);
+typedef FilterXObject *(*FilterXSimpleFunctionProto)(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 void filterx_simple_function_argument_error(FilterXExpr *s, gchar *error_info, gboolean free_info);
 
diff --git a/lib/filterx/filterx-globals.c b/lib/filterx/filterx-globals.c
index 67c977128f..eb6b7176ff 100644
--- a/lib/filterx/filterx-globals.c
+++ b/lib/filterx/filterx-globals.c
@@ -277,14 +277,13 @@ filterx_global_deinit(void)
 }
 
 FilterXObject *
-filterx_typecast_get_arg(FilterXExpr *s, GPtrArray *args)
+filterx_typecast_get_arg(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  if (args == NULL || args->len != 1)
+  if (args == NULL || args_len != 1)
     {
       filterx_simple_function_argument_error(s, "Requires exactly one argument", FALSE);
       return NULL;
     }
 
-  FilterXObject *object = g_ptr_array_index(args, 0);
-  return object;
+  return args[0];
 }
diff --git a/lib/filterx/filterx-globals.h b/lib/filterx/filterx-globals.h
index 7b2bd312e7..b75feb734e 100644
--- a/lib/filterx/filterx-globals.h
+++ b/lib/filterx/filterx-globals.h
@@ -44,6 +44,6 @@ FilterXType *filterx_type_lookup(const gchar *type_name);
 gboolean filterx_type_register(const gchar *type_name, FilterXType *fxtype);
 
 // Helpers
-FilterXObject *filterx_typecast_get_arg(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_typecast_get_arg(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 #endif
diff --git a/lib/filterx/func-len.c b/lib/filterx/func-len.c
index cceb82552d..5aba571681 100644
--- a/lib/filterx/func-len.c
+++ b/lib/filterx/func-len.c
@@ -28,15 +28,15 @@
 #define FILTERX_FUNC_LEN_USAGE "Usage: len(object)"
 
 FilterXObject *
-filterx_simple_function_len(FilterXExpr *s, GPtrArray *args)
+filterx_simple_function_len(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  if (args == NULL || args->len != 1)
+  if (args == NULL || args_len != 1)
     {
       filterx_simple_function_argument_error(s, "Requires exactly one argument", FALSE);
       return NULL;
     }
 
-  FilterXObject *object = g_ptr_array_index(args, 0);
+  FilterXObject *object = args[0];
 
   guint64 len;
   gboolean success = filterx_object_len(object, &len);
diff --git a/lib/filterx/func-len.h b/lib/filterx/func-len.h
index d93909f3ca..ae748c7e80 100644
--- a/lib/filterx/func-len.h
+++ b/lib/filterx/func-len.h
@@ -26,6 +26,6 @@
 
 #include "filterx/expr-function.h"
 
-FilterXObject *filterx_simple_function_len(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_simple_function_len(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 #endif
diff --git a/lib/filterx/func-sdata.c b/lib/filterx/func-sdata.c
index 9e390f8747..5505545bbf 100644
--- a/lib/filterx/func-sdata.c
+++ b/lib/filterx/func-sdata.c
@@ -118,9 +118,9 @@ filterx_function_is_sdata_from_enterprise_new(FilterXFunctionArgs *args, GError
 
 
 FilterXObject *
-filterx_simple_function_has_sdata(FilterXExpr *s, GPtrArray *args)
+filterx_simple_function_has_sdata(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  if (args && args->len != 0)
+  if (args && args_len != 0)
     {
       filterx_simple_function_argument_error(s, "Incorrect number of arguments", FALSE);
       return NULL;
diff --git a/lib/filterx/func-sdata.h b/lib/filterx/func-sdata.h
index a8aec2c161..c457426322 100644
--- a/lib/filterx/func-sdata.h
+++ b/lib/filterx/func-sdata.h
@@ -28,7 +28,7 @@
 #include "filterx/expr-function.h"
 
 FilterXExpr *filterx_function_is_sdata_from_enterprise_new(FilterXFunctionArgs *args, GError **error);
-FilterXObject *filterx_simple_function_has_sdata(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_simple_function_has_sdata(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 FilterXExpr *filterx_generator_function_get_sdata_new(FilterXFunctionArgs *args, GError **error);
 typedef struct FilterXGenFuncGetSdata_
 {
diff --git a/lib/filterx/func-str-transform.c b/lib/filterx/func-str-transform.c
index 6e2a64b84f..fe452791c6 100644
--- a/lib/filterx/func-str-transform.c
+++ b/lib/filterx/func-str-transform.c
@@ -28,9 +28,9 @@
 #include "filterx/filterx-eval.h"
 
 static const gchar *
-_extract_str_arg(FilterXExpr *s, GPtrArray *args, gssize *len)
+_extract_str_arg(FilterXExpr *s, FilterXObject *args[], gsize args_len, gssize *len)
 {
-  if (args == NULL || args->len != 1)
+  if (args == NULL || args_len != 1)
     {
       filterx_simple_function_argument_error(s, "Requires exactly one argument", FALSE);
       return NULL;
@@ -38,7 +38,7 @@ _extract_str_arg(FilterXExpr *s, GPtrArray *args, gssize *len)
 
   const gchar *str;
   gsize inner_len;
-  FilterXObject *object = g_ptr_array_index(args, 0);
+  FilterXObject *object = args[0];
 
   if (!filterx_object_extract_string_ref(object, &str, &inner_len))
     {
@@ -51,10 +51,10 @@ _extract_str_arg(FilterXExpr *s, GPtrArray *args, gssize *len)
 }
 
 FilterXObject *
-filterx_simple_function_lower(FilterXExpr *s, GPtrArray *args)
+filterx_simple_function_lower(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
   gssize len;
-  const gchar *str = _extract_str_arg(s, args, &len);
+  const gchar *str = _extract_str_arg(s, args, args_len, &len);
   if (!str)
     return NULL;
 
@@ -66,10 +66,10 @@ filterx_simple_function_lower(FilterXExpr *s, GPtrArray *args)
 }
 
 FilterXObject *
-filterx_simple_function_upper(FilterXExpr *s, GPtrArray *args)
+filterx_simple_function_upper(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
   gssize len;
-  const gchar *str = _extract_str_arg(s, args, &len);
+  const gchar *str = _extract_str_arg(s, args, args_len, &len);
   if (!str)
     return NULL;
 
diff --git a/lib/filterx/func-str-transform.h b/lib/filterx/func-str-transform.h
index b3d329576c..dbcccdfb1e 100644
--- a/lib/filterx/func-str-transform.h
+++ b/lib/filterx/func-str-transform.h
@@ -27,7 +27,7 @@
 
 #include "filterx/expr-function.h"
 
-FilterXObject *filterx_simple_function_lower(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_simple_function_upper(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_simple_function_lower(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_simple_function_upper(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 #endif
diff --git a/lib/filterx/func-vars.c b/lib/filterx/func-vars.c
index 4251a36140..f78286882c 100644
--- a/lib/filterx/func-vars.c
+++ b/lib/filterx/func-vars.c
@@ -64,9 +64,9 @@ _add_to_dict(FilterXVariable *variable, gpointer user_data)
 }
 
 FilterXObject *
-filterx_simple_function_vars(FilterXExpr *s, GPtrArray *args)
+filterx_simple_function_vars(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  if (args && args->len != 0)
+  if (args && args_len != 0)
     {
       filterx_simple_function_argument_error(s, "Incorrect number of arguments", FALSE);
       return NULL;
@@ -150,15 +150,15 @@ _load_from_dict(FilterXObject *key, FilterXObject *value, gpointer user_data)
 }
 
 FilterXObject *
-filterx_simple_function_load_vars(FilterXExpr *s, GPtrArray *args)
+filterx_simple_function_load_vars(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  if (!args || args->len != 1)
+  if (!args || args_len != 1)
     {
       filterx_simple_function_argument_error(s, "Incorrect number of arguments", FALSE);
       return NULL;
     }
 
-  FilterXObject *vars = g_ptr_array_index(args, 0);
+  FilterXObject *vars = args[0];
   FilterXObject *vars_unwrapped = filterx_ref_unwrap_ro(vars);
   FilterXObject *vars_unmarshalled = NULL;
 
diff --git a/lib/filterx/func-vars.h b/lib/filterx/func-vars.h
index 88d0161efe..63f57c5607 100644
--- a/lib/filterx/func-vars.h
+++ b/lib/filterx/func-vars.h
@@ -26,7 +26,7 @@
 
 #include "filterx/expr-function.h"
 
-FilterXObject *filterx_simple_function_vars(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_simple_function_load_vars(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_simple_function_vars(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_simple_function_load_vars(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 #endif
diff --git a/lib/filterx/object-datetime.c b/lib/filterx/object-datetime.c
index 51517b5835..8e4f373818 100644
--- a/lib/filterx/object-datetime.c
+++ b/lib/filterx/object-datetime.c
@@ -121,9 +121,9 @@ filterx_datetime_get_value(FilterXObject *s)
 
 
 FilterXObject *
-filterx_typecast_datetime(FilterXExpr *s, GPtrArray *args)
+filterx_typecast_datetime(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  FilterXObject *object = filterx_typecast_get_arg(s, args);
+  FilterXObject *object = filterx_typecast_get_arg(s, args, args_len);
   if (!object)
     return NULL;
 
@@ -147,13 +147,13 @@ filterx_typecast_datetime(FilterXExpr *s, GPtrArray *args)
       return filterx_datetime_new(&ut);
     }
 
-  return filterx_typecast_datetime_isodate(s, args);
+  return filterx_typecast_datetime_isodate(s, args, args_len);
 }
 
 FilterXObject *
-filterx_typecast_datetime_isodate(FilterXExpr *s, GPtrArray *args)
+filterx_typecast_datetime_isodate(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  FilterXObject *object = filterx_typecast_get_arg(s, args);
+  FilterXObject *object = filterx_typecast_get_arg(s, args, args_len);
   if (!object)
     return NULL;
 
diff --git a/lib/filterx/object-datetime.h b/lib/filterx/object-datetime.h
index 17e4be1359..d31a0e7fce 100644
--- a/lib/filterx/object-datetime.h
+++ b/lib/filterx/object-datetime.h
@@ -34,8 +34,8 @@ FILTERX_DECLARE_TYPE(datetime);
 
 FilterXObject *filterx_datetime_new(const UnixTime *ut);
 UnixTime filterx_datetime_get_value(FilterXObject *s);
-FilterXObject *filterx_typecast_datetime(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_typecast_datetime_isodate(FilterXExpr *, GPtrArray *args);
+FilterXObject *filterx_typecast_datetime(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_typecast_datetime_isodate(FilterXExpr *, FilterXObject *args[], gsize args_len);
 FilterXExpr *filterx_function_strptime_new(FilterXFunctionArgs *args, GError **error);
 FilterXExpr *filterx_function_strftime_new(FilterXFunctionArgs *args, GError **error);
 
diff --git a/lib/filterx/object-json-array.c b/lib/filterx/object-json-array.c
index 3596461c1c..aa83e12ad7 100644
--- a/lib/filterx/object-json-array.c
+++ b/lib/filterx/object-json-array.c
@@ -316,18 +316,18 @@ filterx_json_array_new_from_syslog_ng_list(const gchar *repr, gssize repr_len)
 }
 
 FilterXObject *
-filterx_json_array_new_from_args(FilterXExpr *s, GPtrArray *args)
+filterx_json_array_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  if (!args || args->len == 0)
+  if (!args || args_len == 0)
     return filterx_json_array_new_empty();
 
-  if (args->len != 1)
+  if (args_len != 1)
     {
       filterx_simple_function_argument_error(s, "Requires zero or one argument", FALSE);
       return NULL;
     }
 
-  FilterXObject *arg = (FilterXObject *) g_ptr_array_index(args, 0);
+  FilterXObject *arg = args[0];
 
   FilterXObject *json_arr = filterx_ref_unwrap_ro(arg);
   if (filterx_object_is_type(json_arr, &FILTERX_TYPE_NAME(json_array)))
diff --git a/lib/filterx/object-json.c b/lib/filterx/object-json.c
index 7fe7125e82..0bd6d10884 100644
--- a/lib/filterx/object-json.c
+++ b/lib/filterx/object-json.c
@@ -186,18 +186,18 @@ filterx_json_new_from_repr(const gchar *repr, gssize repr_len)
 }
 
 FilterXObject *
-filterx_json_new_from_args(FilterXExpr *s, GPtrArray *args)
+filterx_json_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  if (!args || args->len == 0)
+  if (!args || args_len == 0)
     return filterx_json_object_new_empty();
 
-  if (args->len != 1)
+  if (args_len != 1)
     {
       filterx_eval_push_error("Too many arguments", s, NULL);
       return NULL;
     }
 
-  FilterXObject *arg = (FilterXObject *) g_ptr_array_index(args, 0);
+  FilterXObject *arg = args[0];
 
   FilterXObject *arg_unwrapped = filterx_ref_unwrap_ro(arg);
   if (filterx_object_is_type(arg_unwrapped, &FILTERX_TYPE_NAME(json_array)) ||
diff --git a/lib/filterx/object-json.h b/lib/filterx/object-json.h
index 22116b7ce0..3dc79718f4 100644
--- a/lib/filterx/object-json.h
+++ b/lib/filterx/object-json.h
@@ -41,8 +41,8 @@ FilterXObject *filterx_json_array_new_from_syslog_ng_list(const gchar *repr, gss
 FilterXObject *filterx_json_object_new_empty(void);
 FilterXObject *filterx_json_array_new_empty(void);
 
-FilterXObject *filterx_json_new_from_args(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_json_array_new_from_args(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_json_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_json_array_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 FilterXObject *filterx_json_new_from_object(struct json_object *object);
 
diff --git a/lib/filterx/object-metrics-labels.c b/lib/filterx/object-metrics-labels.c
index dc40d53f0d..5bd0a3a11d 100644
--- a/lib/filterx/object-metrics-labels.c
+++ b/lib/filterx/object-metrics-labels.c
@@ -293,9 +293,9 @@ filterx_object_metrics_labels_new(guint reserved_size)
 }
 
 FilterXObject *
-filterx_simple_function_metrics_labels(FilterXExpr *s, GPtrArray *args)
+filterx_simple_function_metrics_labels(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  if (args && args->len)
+  if (args && args_len)
     {
       filterx_simple_function_argument_error(s, "unexpected argument.", FALSE);
       return NULL;
@@ -305,16 +305,16 @@ filterx_simple_function_metrics_labels(FilterXExpr *s, GPtrArray *args)
 }
 
 static FilterXObject *
-_dedup_extract_obj_arg(FilterXExpr *s, GPtrArray *args)
+_dedup_extract_obj_arg(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  if (!args || args->len != 1)
+  if (!args || args_len != 1)
     {
       filterx_simple_function_argument_error(s, "unexpected number of arguments. "
                                              DEDUP_METRICS_LABELS_USAGE, FALSE);
       return NULL;
     }
 
-  FilterXObject *obj = g_ptr_array_index(args, 0);
+  FilterXObject *obj = args[0];
   FilterXObject *typed_obj = filterx_ref_unwrap_ro(obj);
   if (!filterx_object_is_type(typed_obj, &FILTERX_TYPE_NAME(metrics_labels)))
     {
@@ -327,9 +327,9 @@ _dedup_extract_obj_arg(FilterXExpr *s, GPtrArray *args)
 }
 
 FilterXObject *
-filterx_simple_function_dedup_metrics_labels(FilterXExpr *s, GPtrArray *args)
+filterx_simple_function_dedup_metrics_labels(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  FilterXObject *obj = _dedup_extract_obj_arg(s, args);
+  FilterXObject *obj = _dedup_extract_obj_arg(s, args, args_len);
   if (!obj)
     return NULL;
 
diff --git a/lib/filterx/object-metrics-labels.h b/lib/filterx/object-metrics-labels.h
index ffdfbd1687..a7a3622cd9 100644
--- a/lib/filterx/object-metrics-labels.h
+++ b/lib/filterx/object-metrics-labels.h
@@ -32,7 +32,7 @@ FILTERX_DECLARE_TYPE(metrics_labels);
 
 FilterXObject *filterx_object_metrics_labels_new(guint reserved_size);
 StatsClusterLabel *filterx_object_metrics_labels_get_value_ref(FilterXObject *s, gsize *len);
-FilterXObject *filterx_simple_function_metrics_labels(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_simple_function_dedup_metrics_labels(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_simple_function_metrics_labels(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_simple_function_dedup_metrics_labels(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 #endif
diff --git a/lib/filterx/object-primitive.c b/lib/filterx/object-primitive.c
index c0e7030264..ebb894b651 100644
--- a/lib/filterx/object-primitive.c
+++ b/lib/filterx/object-primitive.c
@@ -268,9 +268,9 @@ filterx_primitive_get_value(FilterXObject *s)
 }
 
 FilterXObject *
-filterx_typecast_boolean(FilterXExpr *s, GPtrArray *args)
+filterx_typecast_boolean(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  FilterXObject *object = filterx_typecast_get_arg(s, args);
+  FilterXObject *object = filterx_typecast_get_arg(s, args, args_len);
   if (!object)
     return NULL;
 
@@ -284,9 +284,9 @@ filterx_typecast_boolean(FilterXExpr *s, GPtrArray *args)
 }
 
 FilterXObject *
-filterx_typecast_integer(FilterXExpr *s, GPtrArray *args)
+filterx_typecast_integer(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  FilterXObject *object = filterx_typecast_get_arg(s, args);
+  FilterXObject *object = filterx_typecast_get_arg(s, args, args_len);
   if (!object)
     return NULL;
 
@@ -320,9 +320,9 @@ filterx_typecast_integer(FilterXExpr *s, GPtrArray *args)
 }
 
 FilterXObject *
-filterx_typecast_double(FilterXExpr *s, GPtrArray *args)
+filterx_typecast_double(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  FilterXObject *object = filterx_typecast_get_arg(s, args);
+  FilterXObject *object = filterx_typecast_get_arg(s, args, args_len);
   if (!object)
     return NULL;
 
diff --git a/lib/filterx/object-primitive.h b/lib/filterx/object-primitive.h
index 41898b8811..955207e061 100644
--- a/lib/filterx/object-primitive.h
+++ b/lib/filterx/object-primitive.h
@@ -50,9 +50,9 @@ FilterXObject *filterx_boolean_new(gboolean value);
 FilterXObject *filterx_enum_new(GlobalConfig *cfg, const gchar *namespace_name, const gchar *enum_name);
 GenericNumber filterx_primitive_get_value(FilterXObject *s);
 
-FilterXObject *filterx_typecast_boolean(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_typecast_integer(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_typecast_double(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_typecast_boolean(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_typecast_integer(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_typecast_double(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 gboolean bool_repr(gboolean bool_val, GString *repr);
 gboolean double_repr(double val, GString *repr);
diff --git a/lib/filterx/object-string.c b/lib/filterx/object-string.c
index 23439fc87b..baf45a10fb 100644
--- a/lib/filterx/object-string.c
+++ b/lib/filterx/object-string.c
@@ -264,9 +264,9 @@ filterx_protobuf_new(const gchar *mem, gssize mem_len)
 }
 
 FilterXObject *
-filterx_typecast_string(FilterXExpr *s, GPtrArray *args)
+filterx_typecast_string(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  FilterXObject *object = filterx_typecast_get_arg(s, args);
+  FilterXObject *object = filterx_typecast_get_arg(s, args, args_len);
   if (!object)
     return NULL;
 
@@ -287,9 +287,9 @@ filterx_typecast_string(FilterXExpr *s, GPtrArray *args)
 }
 
 FilterXObject *
-filterx_typecast_bytes(FilterXExpr *s, GPtrArray *args)
+filterx_typecast_bytes(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  FilterXObject *object = filterx_typecast_get_arg(s, args);
+  FilterXObject *object = filterx_typecast_get_arg(s, args, args_len);
   if (!object)
     return NULL;
 
@@ -311,9 +311,9 @@ filterx_typecast_bytes(FilterXExpr *s, GPtrArray *args)
 }
 
 FilterXObject *
-filterx_typecast_protobuf(FilterXExpr *s, GPtrArray *args)
+filterx_typecast_protobuf(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  FilterXObject *object = filterx_typecast_get_arg(s, args);
+  FilterXObject *object = filterx_typecast_get_arg(s, args, args_len);
   if (!object)
     return NULL;
 
diff --git a/lib/filterx/object-string.h b/lib/filterx/object-string.h
index ea2b4b0d70..736ede0cfb 100644
--- a/lib/filterx/object-string.h
+++ b/lib/filterx/object-string.h
@@ -34,9 +34,9 @@ FILTERX_DECLARE_TYPE(protobuf);
 const gchar *filterx_string_get_value_ref(FilterXObject *s, gsize *length);
 const gchar *filterx_bytes_get_value_ref(FilterXObject *s, gsize *length);
 const gchar *filterx_protobuf_get_value_ref(FilterXObject *s, gsize *length);
-FilterXObject *filterx_typecast_string(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_typecast_bytes(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_typecast_protobuf(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_typecast_string(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_typecast_bytes(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_typecast_protobuf(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 FilterXObject *filterx_string_new(const gchar *str, gssize str_len);
 FilterXObject *filterx_bytes_new(const gchar *str, gssize str_len);
diff --git a/modules/examples/filterx/example-filterx-func/example-filterx-func-plugin.c b/modules/examples/filterx/example-filterx-func/example-filterx-func-plugin.c
index a3367c99f3..f26c3dd5ac 100644
--- a/modules/examples/filterx/example-filterx-func/example-filterx-func-plugin.c
+++ b/modules/examples/filterx/example-filterx-func/example-filterx-func-plugin.c
@@ -29,27 +29,27 @@
 #include "filterx/object-primitive.h"
 
 static FilterXObject *
-echo(FilterXExpr *s, GPtrArray *args)
+echo(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
   GString *buf = scratch_buffers_alloc();
   LogMessageValueType t;
 
   if (args == NULL ||
-      args->len < 1)
+      args_len < 1)
     {
       return NULL;
     }
 
-  for (int i = 0; i < args->len; i++)
+  for (int i = 0; i < args_len; i++)
     {
-      if (!filterx_object_marshal(args->pdata[i], buf, &t))
+      if (!filterx_object_marshal(args[i], buf, &t))
         goto exit;
       msg_debug("FILTERX EXAMPLE ECHO",
                 evt_tag_str("value", buf->str),
                 evt_tag_str("type", log_msg_value_type_to_str(t)));
     }
-  if (args->len > 0)
-    return filterx_object_ref(args->pdata[0]);
+  if (args_len > 0)
+    return filterx_object_ref(args[0]);
 exit:
   return filterx_boolean_new(FALSE);
 }
diff --git a/modules/grpc/otel/filterx/object-otel-array.cpp b/modules/grpc/otel/filterx/object-otel-array.cpp
index 333f40f21a..9334802e0b 100644
--- a/modules/grpc/otel/filterx/object-otel-array.cpp
+++ b/modules/grpc/otel/filterx/object-otel-array.cpp
@@ -249,20 +249,20 @@ _filterx_otel_array_clone(FilterXObject *s)
 }
 
 FilterXObject *
-filterx_otel_array_new_from_args(FilterXExpr *s, GPtrArray *args)
+filterx_otel_array_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
   FilterXOtelArray *self = g_new0(FilterXOtelArray, 1);
   _init_instance(self);
 
   try
     {
-      if (!args || args->len == 0)
+      if (!args || args_len == 0)
         {
           self->cpp = new Array(self);
         }
-      else if (args->len == 1)
+      else if (args_len == 1)
         {
-          FilterXObject *arg = (FilterXObject *) g_ptr_array_index(args, 0);
+          FilterXObject *arg = args[0];
 
           FilterXObject *list_arg = filterx_ref_unwrap_ro(arg);
           if (filterx_object_is_type(list_arg, &FILTERX_TYPE_NAME(list)))
diff --git a/modules/grpc/otel/filterx/object-otel-kvlist.cpp b/modules/grpc/otel/filterx/object-otel-kvlist.cpp
index 1794143954..956d1f6f3a 100644
--- a/modules/grpc/otel/filterx/object-otel-kvlist.cpp
+++ b/modules/grpc/otel/filterx/object-otel-kvlist.cpp
@@ -364,20 +364,20 @@ _filterx_otel_kvlist_clone(FilterXObject *s)
 }
 
 FilterXObject *
-filterx_otel_kvlist_new_from_args(FilterXExpr *s, GPtrArray *args)
+filterx_otel_kvlist_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
   FilterXOtelKVList *self = g_new0(FilterXOtelKVList, 1);
   _init_instance(self);
 
   try
     {
-      if (!args || args->len == 0)
+      if (!args || args_len == 0)
         {
           self->cpp = new KVList(self);
         }
-      else if (args->len == 1)
+      else if (args_len == 1)
         {
-          FilterXObject *arg = (FilterXObject *) g_ptr_array_index(args, 0);
+          FilterXObject *arg = args[0];
           FilterXObject *dict_arg = filterx_ref_unwrap_ro(arg);
           if (filterx_object_is_type(dict_arg, &FILTERX_TYPE_NAME(dict)))
             {
diff --git a/modules/grpc/otel/filterx/object-otel-logrecord.cpp b/modules/grpc/otel/filterx/object-otel-logrecord.cpp
index 596ea515fe..f021cbf9f3 100644
--- a/modules/grpc/otel/filterx/object-otel-logrecord.cpp
+++ b/modules/grpc/otel/filterx/object-otel-logrecord.cpp
@@ -281,20 +281,20 @@ _filterx_otel_logrecord_clone(FilterXObject *s)
 }
 
 FilterXObject *
-filterx_otel_logrecord_new_from_args(FilterXExpr *s, GPtrArray *args)
+filterx_otel_logrecord_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
   FilterXOtelLogRecord *self = g_new0(FilterXOtelLogRecord, 1);
   _init_instance(self);
 
   try
     {
-      if (!args || args->len == 0)
+      if (!args || args_len == 0)
         {
           self->cpp = new LogRecord(self);
         }
-      else if (args->len == 1)
+      else if (args_len == 1)
         {
-          FilterXObject *arg = (FilterXObject *) g_ptr_array_index(args, 0);
+          FilterXObject *arg = args[0];
           FilterXObject *dict_arg = filterx_ref_unwrap_ro(arg);
           if (filterx_object_is_type(dict_arg, &FILTERX_TYPE_NAME(dict)))
             {
diff --git a/modules/grpc/otel/filterx/object-otel-resource.cpp b/modules/grpc/otel/filterx/object-otel-resource.cpp
index 475b32e314..f725939fd3 100644
--- a/modules/grpc/otel/filterx/object-otel-resource.cpp
+++ b/modules/grpc/otel/filterx/object-otel-resource.cpp
@@ -267,20 +267,20 @@ _filterx_otel_resource_clone(FilterXObject *s)
 }
 
 FilterXObject *
-filterx_otel_resource_new_from_args(FilterXExpr *s, GPtrArray *args)
+filterx_otel_resource_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
   FilterXOtelResource *self = g_new0(FilterXOtelResource, 1);
   _init_instance(self);
 
   try
     {
-      if (!args || args->len == 0)
+      if (!args || args_len == 0)
         {
           self->cpp = new Resource(self);
         }
-      else if (args->len == 1)
+      else if (args_len == 1)
         {
-          FilterXObject *arg = (FilterXObject *) g_ptr_array_index(args, 0);
+          FilterXObject *arg = args[0];
           FilterXObject *dict_arg = filterx_ref_unwrap_ro(arg);
           if (filterx_object_is_type(dict_arg, &FILTERX_TYPE_NAME(dict)))
             {
diff --git a/modules/grpc/otel/filterx/object-otel-scope.cpp b/modules/grpc/otel/filterx/object-otel-scope.cpp
index ead2c40c10..c6b2703d57 100644
--- a/modules/grpc/otel/filterx/object-otel-scope.cpp
+++ b/modules/grpc/otel/filterx/object-otel-scope.cpp
@@ -267,20 +267,20 @@ _filterx_otel_scope_clone(FilterXObject *s)
 }
 
 FilterXObject *
-filterx_otel_scope_new_from_args(FilterXExpr *s, GPtrArray *args)
+filterx_otel_scope_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
   FilterXOtelScope *self = g_new0(FilterXOtelScope, 1);
   _init_instance(self);
 
   try
     {
-      if (!args || args->len == 0)
+      if (!args || args_len == 0)
         {
           self->cpp = new Scope(self);
         }
-      else if (args->len == 1)
+      else if (args_len == 1)
         {
-          FilterXObject *arg = (FilterXObject *) g_ptr_array_index(args, 0);
+          FilterXObject *arg = args[0];
           FilterXObject *dict_arg = filterx_ref_unwrap_ro(arg);
           if (filterx_object_is_type(dict_arg, &FILTERX_TYPE_NAME(dict)))
             {
diff --git a/modules/grpc/otel/filterx/object-otel.h b/modules/grpc/otel/filterx/object-otel.h
index 313787410b..c5da73077b 100644
--- a/modules/grpc/otel/filterx/object-otel.h
+++ b/modules/grpc/otel/filterx/object-otel.h
@@ -36,40 +36,40 @@ FILTERX_SIMPLE_FUNCTION_DECLARE(otel_kvlist);
 FILTERX_SIMPLE_FUNCTION_DECLARE(otel_array);
 
 
-FilterXObject *filterx_otel_logrecord_new_from_args(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_otel_resource_new_from_args(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_otel_scope_new_from_args(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_otel_kvlist_new_from_args(FilterXExpr *s, GPtrArray *args);
-FilterXObject *filterx_otel_array_new_from_args(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_otel_logrecord_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_otel_resource_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_otel_scope_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_otel_kvlist_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len);
+FilterXObject *filterx_otel_array_new_from_args(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 static inline FilterXObject *
 filterx_otel_logrecord_new(void)
 {
-  return filterx_otel_logrecord_new_from_args(NULL, NULL);
+  return filterx_otel_logrecord_new_from_args(NULL, NULL, 0);
 }
 
 static inline FilterXObject *
 filterx_otel_resource_new(void)
 {
-  return filterx_otel_resource_new_from_args(NULL, NULL);
+  return filterx_otel_resource_new_from_args(NULL, NULL, 0);
 }
 
 static inline FilterXObject *
 filterx_otel_scope_new(void)
 {
-  return filterx_otel_scope_new_from_args(NULL, NULL);
+  return filterx_otel_scope_new_from_args(NULL, NULL, 0);
 }
 
 static inline FilterXObject *
 filterx_otel_kvlist_new(void)
 {
-  return filterx_otel_kvlist_new_from_args(NULL, NULL);
+  return filterx_otel_kvlist_new_from_args(NULL, NULL, 0);
 }
 
 static inline FilterXObject *
 filterx_otel_array_new(void)
 {
-  return filterx_otel_array_new_from_args(NULL, NULL);
+  return filterx_otel_array_new_from_args(NULL, NULL, 0);
 }
 
 gpointer grpc_otel_filterx_enum_construct(Plugin *self);
diff --git a/modules/json/filterx-format-json.c b/modules/json/filterx-format-json.c
index 79051e561a..4af6ab0cd8 100644
--- a/modules/json/filterx-format-json.c
+++ b/modules/json/filterx-format-json.c
@@ -297,16 +297,16 @@ _format_json(FilterXObject *arg)
 }
 
 FilterXObject *
-filterx_format_json_call(FilterXExpr *s, GPtrArray *args)
+filterx_format_json_call(FilterXExpr *s, FilterXObject *args[], gsize args_len)
 {
-  if (!args || args->len != 1)
+  if (!args || args_len != 1)
     {
       msg_error("FilterX: format_json(): Invalid number of arguments. "
                 "Usage: format_json($data)");
       return NULL;
     }
 
-  FilterXObject *arg = (FilterXObject *) g_ptr_array_index(args, 0);
+  FilterXObject *arg = args[0];
   return _format_json(arg);
 }
 
diff --git a/modules/json/filterx-format-json.h b/modules/json/filterx-format-json.h
index 0e495b61c3..e598163f8c 100644
--- a/modules/json/filterx-format-json.h
+++ b/modules/json/filterx-format-json.h
@@ -24,7 +24,7 @@
 #include "filterx/filterx-object.h"
 #include "filterx/expr-function.h"
 
-FilterXObject *filterx_format_json_call(FilterXExpr *s, GPtrArray *args);
+FilterXObject *filterx_format_json_call(FilterXExpr *s, FilterXObject *args[], gsize args_len);
 
 FILTERX_SIMPLE_FUNCTION_DECLARE(format_json);