diff --git a/src/verify/verifier.rs b/src/verify/verifier.rs
index 818888996a..ac4d4f62b3 100644
--- a/src/verify/verifier.rs
+++ b/src/verify/verifier.rs
@@ -160,7 +160,7 @@ impl AsyncVerifier {
             .not_after
             .to_unix_duration()
             .as_secs();
-        if !(not_before <= integrated_time && integrated_time <= not_after) {
+        if integrated_time < not_before || integrated_time > not_after {
             return Err(CertificateErrorKind::Expired)?;
         }
         debug!("data signed during validity period");