diff --git a/openssl/src/x509/mod.rs b/openssl/src/x509/mod.rs
index 649dfdc2..12a122b2 100644
--- a/openssl/src/x509/mod.rs
+++ b/openssl/src/x509/mod.rs
@@ -433,7 +433,7 @@ impl<'a> X509Ref<'a> {
         }
     }
 
-    /// Returns certificate Not Before validity period.
+    /// Returns certificate Not After validity period.
     /// Requires the `x509_expiry` feature.
     #[cfg(feature = "x509_expiry")]
     pub fn not_after(&self) -> Asn1TimeRef {
@@ -444,7 +444,7 @@ impl<'a> X509Ref<'a> {
         }
     }
 
-    /// Returns certificate Not After validity period.
+    /// Returns certificate Not Before validity period.
     /// Requires the `x509_expiry` feature.
     #[cfg(feature = "x509_expiry")]
     pub fn not_before(&self) -> Asn1TimeRef {