diff --git a/include/openssl/x509.h b/include/openssl/x509.h
index 72f7314..ee3eccc 100644
--- a/include/openssl/x509.h
+++ b/include/openssl/x509.h
@@ -1200,5 +1200,6 @@
 #define X509_R_WRONG_TYPE 134
 #define X509_R_NAME_TOO_LONG 135
 #define X509_R_INVALID_PARAMETER 136
+#define X509_R_SIGNATURE_ALGORITHM_MISMATCH 137
 
 #endif