diff --git a/openssl-sys/src/asn1.rs b/openssl-sys/src/asn1.rs
index e86528f6..042b3eca 100644
--- a/openssl-sys/src/asn1.rs
+++ b/openssl-sys/src/asn1.rs
@@ -49,6 +49,7 @@ extern "C" {
     pub fn ASN1_INTEGER_to_BN(ai: *const ASN1_INTEGER, bn: *mut BIGNUM) -> *mut BIGNUM;
 
     pub fn ASN1_TIME_set_string(s: *mut ASN1_TIME, str: *const c_char) -> c_int;
+    #[cfg(ossl111)]
     pub fn ASN1_TIME_set_string_X509(s: *mut ASN1_TIME, str: *const c_char) -> c_int;
 }
 
diff --git a/openssl/src/asn1.rs b/openssl/src/asn1.rs
index 5cbeeb0d..911f3462 100644
--- a/openssl/src/asn1.rs
+++ b/openssl/src/asn1.rs
@@ -149,7 +149,10 @@ impl Asn1Time {
     ///
     /// This corresponds to [`ASN1_TIME_set_string_X509`].
     ///
+    /// Requires OpenSSL 1.1.1 or newer.
+    ///
     /// [`ASN1_TIME_set_string`]: https://www.openssl.org/docs/manmaster/man3/ASN1_TIME_set_string.html
+    #[cfg(ossl111)]
     pub fn from_str_x509(s: &str) -> Result<Asn1Time, ErrorStack> {
         unsafe {
             let s = CString::new(s).unwrap();
@@ -385,6 +388,7 @@ mod tests {
     #[test]
     fn time_from_str() {
         Asn1Time::from_str("99991231235959Z").unwrap();
+        #[cfg(ossl111)]
         Asn1Time::from_str_x509("99991231235959Z").unwrap();
     }
 }