--- a/crates/jrsonnet-stdlib/src/lib.rs
+++ b/crates/jrsonnet-stdlib/src/lib.rs
@@ -104,6 +104,7 @@
 		("exp", builtin_exp::INST),
 		("mantissa", builtin_mantissa::INST),
 		("exponent", builtin_exponent::INST),
+		("round", builtin_round::INST),
 		// Operator
 		("mod", builtin_mod::INST),
 		("primitiveEquals", builtin_primitive_equals::INST),
--- a/crates/jrsonnet-stdlib/src/math.rs
+++ b/crates/jrsonnet-stdlib/src/math.rs
@@ -114,3 +114,8 @@
 pub fn builtin_exponent(x: f64) -> i16 {
 	frexp(x).1
 }
+
+#[builtin]
+pub fn builtin_round(x: f64) -> f64 {
+	x.round()
+}