diff --git a/include/polarssl/compat-1.2.h b/include/polarssl/compat-1.2.h
index c0d7e01..70c544b 100644
--- a/include/polarssl/compat-1.2.h
+++ b/include/polarssl/compat-1.2.h
@@ -29,8 +29,13 @@
 
 #include "config.h"
 
+// Comment out to disable prototype change warnings
 #define SHOW_PROTOTYPE_CHANGE_WARNINGS
 
+#if defined(SHOW_PROTOTYPE_CHANGE_WARNINGS)
+#warning "You can disable these warnings by commenting SHOW_PROTOTYPE_CHANGE_WARNINGS in compat-1.2.h"
+#endif
+
 #if defined(POLARSSL_SHA256_C)
 #define POLARSSL_SHA2_C
 #include "sha256.h"
@@ -169,6 +174,20 @@
 #endif
 #endif
 
+#if defined(POLARSSL_X509_USE_C) || defined(POLARSSL_X509_CREATE_C)
+#define POLARSSL_ERR_X509_CERT_INVALID_FORMAT POLARSSL_ERR_X509_INVALID_FORMAT
+#define POLARSSL_ERR_X509_CERT_INVALID_VERSION POLARSSL_ERR_X509_INVALID_VERSION
+#define POLARSSL_ERR_X509_CERT_INVALID_ALG POLARSSL_ERR_X509_INVALID_ALG
+#define POLARSSL_ERR_X509_CERT_UNKNOWN_SIG_ALG POLARSSL_ERR_X509_UNKNOWN_SIG_ALG
+#define POLARSSL_ERR_X509_CERT_INVALID_NAME POLARSSL_ERR_X509_INVALID_NAME
+#define POLARSSL_ERR_X509_CERT_INVALID_DATE POLARSSL_ERR_X509_INVALID_DATE
+#define POLARSSL_ERR_X509_CERT_INVALID_EXTENSIONS POLARSSL_ERR_X509_INVALID_EXTENSIONS
+#define POLARSSL_ERR_X509_CERT_SIG_MISMATCH POLARSSL_ERR_X509_SIG_MISMATCH
+#define POLARSSL_ERR_X509_CERT_INVALID_SIGNATURE POLARSSL_ERR_X509_INVALID_SIGNATURE
+#define POLARSSL_ERR_X509_CERT_INVALID_SERIAL POLARSSL_ERR_X509_INVALID_SERIAL
+#define POLARSSL_ERR_X509_CERT_UNKNOWN_VERSION POLARSSL_ERR_X509_UNKNOWN_VERSION
+#endif /* POLARSSL_X509_USE_C || POLARSSL_X509_CREATE_C */
+
 #if defined(POLARSSL_X509_CRT_PARSE_C)
 #define POLARSSL_X509_PARSE_C
 #include "x509_crt.h"
diff --git a/include/polarssl/error.h b/include/polarssl/error.h
index 205a105..0c9e451 100644
--- a/include/polarssl/error.h
+++ b/include/polarssl/error.h
@@ -83,7 +83,6 @@
  * RSA       4   9
  * ECP       4   4 (Started from top)
  * MD        5   4
- * X509WRITE 5   3 (Started from top)
  * CIPHER    6   5
  * SSL       6   6 (Started from top)
  * SSL       7   31
diff --git a/include/polarssl/x509.h b/include/polarssl/x509.h
index 0e4db60..17eefad 100644
--- a/include/polarssl/x509.h
+++ b/include/polarssl/x509.h
@@ -46,26 +46,23 @@
  * \{
  */
 #define POLARSSL_ERR_X509_FEATURE_UNAVAILABLE              -0x2080  /**< Unavailable feature, e.g. RSA hashing/encryption combination. */
-#define POLARSSL_ERR_X509_CERT_INVALID_PEM                 -0x2100  /**< The PEM-encoded certificate contains invalid elements, e.g. invalid character. */ 
-#define POLARSSL_ERR_X509_CERT_INVALID_FORMAT              -0x2180  /**< The certificate format is invalid, e.g. different type expected. */
-#define POLARSSL_ERR_X509_CERT_INVALID_VERSION             -0x2200  /**< The certificate version element is invalid. */
-#define POLARSSL_ERR_X509_CERT_INVALID_SERIAL              -0x2280  /**< The serial tag or value is invalid. */
-#define POLARSSL_ERR_X509_CERT_INVALID_ALG                 -0x2300  /**< The algorithm tag or value is invalid. */
-#define POLARSSL_ERR_X509_CERT_INVALID_NAME                -0x2380  /**< The name tag or value is invalid. */
-#define POLARSSL_ERR_X509_CERT_INVALID_DATE                -0x2400  /**< The date tag or value is invalid. */
-#define POLARSSL_ERR_X509_CERT_INVALID_SIGNATURE           -0x2480  /**< The signature tag or value invalid. */
-#define POLARSSL_ERR_X509_CERT_INVALID_EXTENSIONS          -0x2500  /**< The extension tag or value is invalid. */
-#define POLARSSL_ERR_X509_CERT_UNKNOWN_VERSION             -0x2580  /**< Certificate or CRL has an unsupported version number. */
-#define POLARSSL_ERR_X509_CERT_UNKNOWN_SIG_ALG             -0x2600  /**< Signature algorithm (oid) is unsupported. */
-#define POLARSSL_ERR_X509_CERT_SIG_MISMATCH                -0x2680  /**< Certificate signature algorithms do not match. (see \c ::x509_cert sig_oid) */
+#define POLARSSL_ERR_X509_UNKNOWN_OID                      -0x2100  /**< Requested OID is unknown. */
+#define POLARSSL_ERR_X509_INVALID_FORMAT                   -0x2180  /**< The CRT/CRL/CSR format is invalid, e.g. different type expected. */
+#define POLARSSL_ERR_X509_INVALID_VERSION                  -0x2200  /**< The CRT/CRL/CSR version element is invalid. */
+#define POLARSSL_ERR_X509_INVALID_SERIAL                   -0x2280  /**< The serial tag or value is invalid. */
+#define POLARSSL_ERR_X509_INVALID_ALG                      -0x2300  /**< The algorithm tag or value is invalid. */
+#define POLARSSL_ERR_X509_INVALID_NAME                     -0x2380  /**< The name tag or value is invalid. */
+#define POLARSSL_ERR_X509_INVALID_DATE                     -0x2400  /**< The date tag or value is invalid. */
+#define POLARSSL_ERR_X509_INVALID_SIGNATURE                -0x2480  /**< The signature tag or value invalid. */
+#define POLARSSL_ERR_X509_INVALID_EXTENSIONS               -0x2500  /**< The extension tag or value is invalid. */
+#define POLARSSL_ERR_X509_UNKNOWN_VERSION                  -0x2580  /**< CRT/CRL/CSR has an unsupported version number. */
+#define POLARSSL_ERR_X509_UNKNOWN_SIG_ALG                  -0x2600  /**< Signature algorithm (oid) is unsupported. */
+#define POLARSSL_ERR_X509_SIG_MISMATCH                     -0x2680  /**< Signature algorithms do not match. (see \c ::x509_cert sig_oid) */
 #define POLARSSL_ERR_X509_CERT_VERIFY_FAILED               -0x2700  /**< Certificate verification failed, e.g. CRL, CA or signature check failed. */
 #define POLARSSL_ERR_X509_CERT_UNKNOWN_FORMAT              -0x2780  /**< Format not recognized as DER or PEM. */
-#define POLARSSL_ERR_X509_INVALID_INPUT                    -0x2800  /**< Input invalid. */
+#define POLARSSL_ERR_X509_BAD_INPUT_DATA                   -0x2800  /**< Input invalid. */
 #define POLARSSL_ERR_X509_MALLOC_FAILED                    -0x2880  /**< Allocation of memory failed. */
 #define POLARSSL_ERR_X509_FILE_IO_ERROR                    -0x2900  /**< Read/write of file failed. */
-#define POLARSSL_ERR_X509WRITE_UNKNOWN_OID                -0x5F80  /**< Requested OID is unknown. */
-#define POLARSSL_ERR_X509WRITE_BAD_INPUT_DATA             -0x5F00  /**< Failed to allocate memory. */
-#define POLARSSL_ERR_X509WRITE_MALLOC_FAILED              -0x5E80  /**< Failed to allocate memory. */
 /* \} name */
 
 /**