diff --git a/openssl-sys/build/cfgs.rs b/openssl-sys/build/cfgs.rs
index 91cb734c3..e4b6a4d91 100644
--- a/openssl-sys/build/cfgs.rs
+++ b/openssl-sys/build/cfgs.rs
@@ -65,6 +65,9 @@ pub fn get(openssl_version: Option<u64>, libressl_version: Option<u64>) -> Vec<&
         if libressl_version >= 0x3_09_00_00_0 {
             cfgs.push("libressl390");
         }
+        if libressl_version >= 0x4_00_00_00_0 {
+            cfgs.push("libressl400");
+        }
     } else {
         let openssl_version = openssl_version.unwrap();
 
diff --git a/openssl-sys/src/handwritten/x509.rs b/openssl-sys/src/handwritten/x509.rs
index 7642dcd3b..0bb682764 100644
--- a/openssl-sys/src/handwritten/x509.rs
+++ b/openssl-sys/src/handwritten/x509.rs
@@ -1,10 +1,16 @@
 use super::super::*;
 use libc::*;
 
-#[repr(C)]
-pub struct X509_VAL {
-    pub notBefore: *mut ASN1_TIME,
-    pub notAfter: *mut ASN1_TIME,
+cfg_if! {
+    if #[cfg(libressl400)] {
+        pub enum X509_VAL {}
+    } else {
+        #[repr(C)]
+        pub struct X509_VAL {
+            pub notBefore: *mut ASN1_TIME,
+            pub notAfter: *mut ASN1_TIME,
+        }
+    }
 }
 
 pub enum X509_NAME_ENTRY {}