diff --git a/src/hazardous/ecc/x25519.rs b/src/hazardous/ecc/x25519.rs
index 02ddb8e6..e10e5fc7 100644
--- a/src/hazardous/ecc/x25519.rs
+++ b/src/hazardous/ecc/x25519.rs
@@ -399,7 +399,7 @@ mod public {
 
         let mut u = [0u8; 32];
         crate::util::secure_rand_bytes(&mut u).unwrap();
-        debug_assert_ne!(u[31] & 127u8, u[31] | 128u8);
+        debug_assert_ne!(u[31] & 127u8, (u[31] & 127u8) | 128u8);
 
         // Mask bit to 0 as we do in `FieldElement::from_bytes()`.
         u[31] &= 127u8;