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"