diff --git a/duckdb-rfuns-r/R/aggregate.R b/duckdb-rfuns-r/R/aggregate.R
index 168c964..9f45d74 100644
--- a/duckdb-rfuns-r/R/aggregate.R
+++ b/duckdb-rfuns-r/R/aggregate.R
@@ -11,18 +11,17 @@
 #' @rdname aggregate
 #' @export
 rfuns_sum <- function(x, ...) {
-  rfuns("aggregate", "sum", tibble(x = x), ...)
+  rfuns("sum", tibble(x = x), ..., op = "aggregate")
 }
 
 #' @rdname aggregate
 #' @export
 rfuns_min <- function(x, ...) {
-  rfuns("aggregate", "min", tibble(x = x), ...)
+  rfuns("min", tibble(x = x), ..., op = "aggregate")
 }
 
 #' @rdname aggregate
 #' @export
 rfuns_max <- function(x, ...) {
-  rfuns("aggregate", "max", tibble(x = x), ...)
+  rfuns("max", tibble(x = x), ..., op = "aggregate")
 }
-
diff --git a/duckdb-rfuns-r/R/project.R b/duckdb-rfuns-r/R/project.R
index bb9222b..5898357 100644
--- a/duckdb-rfuns-r/R/project.R
+++ b/duckdb-rfuns-r/R/project.R
@@ -4,7 +4,7 @@
 #'
 #' @export
 rfuns_is.na <- function(x) {
-  rfuns("project", "is.na", tibble(x = x))
+  rfuns("is.na", tibble(x = x))
 }
 
 #' as.integer()
@@ -13,7 +13,7 @@ rfuns_is.na <- function(x) {
 #'
 #' @export
 rfuns_as.integer <- function(x) {
-  rfuns("project", "as.integer", tibble(x = x))
+  rfuns("as.integer", tibble(x = x))
 }
 
 #' as.numeric()
@@ -22,5 +22,5 @@ rfuns_as.integer <- function(x) {
 #'
 #' @export
 rfuns_as.numeric <- function(x) {
-  rfuns("project", "as.numeric", tibble(x = x))
+  rfuns("as.numeric", tibble(x = x))
 }
diff --git a/duckdb-rfuns-r/R/rfuns.R b/duckdb-rfuns-r/R/rfuns.R
index 8b33e23..5b4b647 100644
--- a/duckdb-rfuns-r/R/rfuns.R
+++ b/duckdb-rfuns-r/R/rfuns.R
@@ -1,4 +1,4 @@
-rfuns <- function(op = c("project", "aggregate"), fun, data, ..., error_call = caller_env()) {
+rfuns <- function(fun, data, ..., error_call = caller_env(), op = c("project", "aggregate")) {
   withr::local_options(list(duckdb.materialize_message = FALSE))
   con <- local_duckdb_con()
 
@@ -13,6 +13,7 @@ rfuns <- function(op = c("project", "aggregate"), fun, data, ..., error_call = c
     )
   )
 
+  op <- rlang::arg_match(op, error_call = error_call)
   result <- switch(op,
     "project"   = duckdb:::rel_project(in_rel, exprs),
     "aggregate" = duckdb:::rel_aggregate(in_rel, list(), exprs)
diff --git a/duckdb-rfuns-r/tests/testthat/test-sum.R b/duckdb-rfuns-r/tests/testthat/test-sum.R
index fce0d9c..c99d881 100644
--- a/duckdb-rfuns-r/tests/testthat/test-sum.R
+++ b/duckdb-rfuns-r/tests/testthat/test-sum.R
@@ -2,13 +2,13 @@ test_that("r_base::sum(<BOOLEAN>)", {
   x <- c(TRUE, TRUE, FALSE, NA)
   empty <- logical()
 
-  expect_equal(rfuns_sum(x, na.rm = TRUE) , sum(x, na.rm = TRUE))
-  expect_equal(rfuns_sum(x, na.rm = FALSE), sum(x, na.rm = FALSE))
+  expect_equal(rfuns_sum(x, na.rm = TRUE)[1] , sum(x, na.rm = TRUE))
+  expect_equal(rfuns_sum(x, na.rm = FALSE)[1], sum(x, na.rm = FALSE))
   expect_equal(rfuns_sum(empty, na.rm = FALSE), sum(empty, na.rm = TRUE))
   expect_equal(rfuns_sum(empty, na.rm = TRUE) , sum(empty, na.rm = FALSE))
 
-  expect_equal(rfuns_sum(x) , sum(x))
-  expect_equal(rfuns_sum(x), sum(x))
+  expect_equal(rfuns_sum(x)[1] , sum(x))
+  expect_equal(rfuns_sum(x)[1], sum(x))
   expect_equal(rfuns_sum(empty), sum(empty))
   expect_equal(rfuns_sum(empty), sum(empty))
 })
diff --git a/src/include/rfuns_extension.hpp b/src/include/rfuns_extension.hpp
index 0940b99..df8271f 100644
--- a/src/include/rfuns_extension.hpp
+++ b/src/include/rfuns_extension.hpp
@@ -63,7 +63,7 @@ ScalarFunctionSet base_r_is_na();
 ScalarFunctionSet base_r_as_integer();
 ScalarFunctionSet base_r_as_numeric();
 
-// sum
+// aggregates
 AggregateFunctionSet base_r_sum();
 AggregateFunctionSet base_r_min();
 AggregateFunctionSet base_r_max();