diff --git a/src/nodes/tests.rs b/src/nodes/tests.rs
index 9e3202b..4c3caa6 100644
--- a/src/nodes/tests.rs
+++ b/src/nodes/tests.rs
@@ -4,6 +4,18 @@ use rug::Float;
 
 use crate::nodes::{Function, Node, Nodes, Operator, PREC};
 
+#[test]
+fn constants() {
+    assert_eq!(
+        Nodes::from_str("c").unwrap().evaluate().to_f64(),
+        299792458.
+    );
+    assert_eq!(
+        Nodes::from_str("A").unwrap().evaluate().to_f64(),
+        6.02214076e23
+    );
+}
+
 #[test]
 fn unary_operators() {
     assert_eq!(Nodes::from_str("-10").unwrap().evaluate().to_f64(), -10.);