diff --git a/Cargo.lock b/Cargo.lock
index f4a518ac..46d7ef93 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1169,9 +1169,9 @@ dependencies = [
 
 [[package]]
 name = "sm3"
-version = "0.4.1"
+version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f943a7c5e3089f2bd046221d1e9f4fa59396bf0fe966360983649683086215da"
+checksum = "ebb9a3b702d0a7e33bc4d85a14456633d2b165c2ad839c5fd9a8417c1ab15860"
 dependencies = [
  "digest",
 ]
diff --git a/primeorder/src/affine.rs b/primeorder/src/affine.rs
index e7f2fecc..3fb01d90 100644
--- a/primeorder/src/affine.rs
+++ b/primeorder/src/affine.rs
@@ -182,8 +182,11 @@ where
             }
             sec1::Coordinates::Uncompressed { x, y } => {
                 C::FieldElement::from_repr(*y).and_then(|y| {
-                    Self::decompress(x, y.is_odd())
-                        .and_then(|point| CtOption::new(point, point.y.ct_eq(&y)))
+                    C::FieldElement::from_repr(*x).and_then(|x| {
+                        let lhs = y * &y;
+                        let rhs = x * &x * &x + &(C::EQUATION_A * &x) + &C::EQUATION_B;
+                        CtOption::new(Self { x, y, infinity: 0 }, lhs.ct_eq(&rhs))
+                    })
                 })
             }
         }