diff --git a/src/moments/mod.rs b/src/moments/mod.rs
index 33225bf..034262a 100644
--- a/src/moments/mod.rs
+++ b/src/moments/mod.rs
@@ -125,14 +125,16 @@ macro_rules! define_moments {
             /// Estimate the `p`th standardized moment of the population.
             #[inline]
             pub fn standardized_moment(&self, p: usize) -> f64 {
-                let variance = self.central_moment(2);
-                assert_ne!(variance, 0.);
-                let n = f64::approx_from(self.n).unwrap();
                 match p {
                     0 => n,
                     1 => 0.,
                     2 => 1.,
-                    _ => self.central_moment(p) / pow(variance.sqrt(), p),
+                    _ => {
+                        let variance = self.central_moment(2);
+                        assert_ne!(variance, 0.);
+                        let n = f64::approx_from(self.n).unwrap();
+                        self.central_moment(p) / pow(variance.sqrt(), p)
+                    },
                 }
             }
 
diff --git a/tests/moments.rs b/tests/moments.rs
index a1fc3bf..85d60a7 100644
--- a/tests/moments.rs
+++ b/tests/moments.rs
@@ -14,6 +14,8 @@ use average::{Moments4, Merge};
 fn trivial() {
     let mut a = Moments4::new();
     assert_eq!(a.len(), 0);
+    assert_eq!(a.central_moment(1), 0.0);
+    assert_eq!(a.standardized_moment(2), 1.0);
     a.add(1.0);
     assert_eq!(a.len(), 1);
     assert_eq!(a.mean(), 1.0);