diff --git a/pyargus/src/expr.rs b/pyargus/src/expr.rs
index ef9a72b..a7a49b4 100644
--- a/pyargus/src/expr.rs
+++ b/pyargus/src/expr.rs
@@ -65,6 +65,10 @@ impl PyNumExpr {
         format!("{:?}", &self.0)
     }
 
+    fn __str__(&self) -> String {
+        format!("{}", self.0)
+    }
+
     fn __neg__(&self) -> PyResult<Py<Negate>> {
         Python::with_gil(|py| Py::new(py, Negate::new(self.clone())))
     }
@@ -308,6 +312,10 @@ impl PyBoolExpr {
         format!("{:?}", &self.0)
     }
 
+    fn __str__(&self) -> String {
+        format!("{}", self.0)
+    }
+
     fn __invert__(&self) -> PyResult<Py<Not>> {
         Python::with_gil(|py| Py::new(py, Not::new(self.clone())))
     }