diff --git a/include/polarssl/x509.h b/include/polarssl/x509.h
index 829adaf..2a05318 100644
--- a/include/polarssl/x509.h
+++ b/include/polarssl/x509.h
@@ -122,7 +122,7 @@
 #define OID_CN                  "\x55\x04\x03"
 #define OID_PKCS1               "\x2A\x86\x48\x86\xF7\x0D\x01\x01"
 #define OID_PKCS1_RSA           "\x2A\x86\x48\x86\xF7\x0D\x01\x01\x01"
-#define OID_PKCS1_RSA_SHA       "\x2A\x86\x48\x86\xF7\x0D\x01\x01\x05"
+#define OID_RSA_SHA_OBS         "\x2B\x0E\x03\x02\x1D"
 #define OID_PKCS9               "\x2A\x86\x48\x86\xF7\x0D\x01\x09"
 #define OID_PKCS9_EMAIL         "\x2A\x86\x48\x86\xF7\x0D\x01\x09\x01"