diff --git a/library/x509_crt.c b/library/x509_crt.c
index c3adf7c..af6c2a4 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -970,7 +970,9 @@
 int mbedtls_x509_crt_parse( mbedtls_x509_crt *chain, const unsigned char *buf, size_t buflen )
 {
     int success = 0, first_error = 0, total_failed = 0;
+#if defined(MBEDTLS_PEM_PARSE_C)
     int buf_format = MBEDTLS_X509_FORMAT_DER;
+#endif
 
     /*
      * Check for valid input
@@ -988,10 +990,12 @@
     {
         buf_format = MBEDTLS_X509_FORMAT_PEM;
     }
-#endif
 
     if( buf_format == MBEDTLS_X509_FORMAT_DER )
         return mbedtls_x509_crt_parse_der( chain, buf, buflen );
+#else
+    return mbedtls_x509_crt_parse_der( chain, buf, buflen );
+#endif
 
 #if defined(MBEDTLS_PEM_PARSE_C)
     if( buf_format == MBEDTLS_X509_FORMAT_PEM )
@@ -1064,7 +1068,6 @@
             success = 1;
         }
     }
-#endif /* MBEDTLS_PEM_PARSE_C */
 
     if( success )
         return( total_failed );
@@ -1072,6 +1075,7 @@
         return( first_error );
     else
         return( MBEDTLS_ERR_X509_CERT_UNKNOWN_FORMAT );
+#endif /* MBEDTLS_PEM_PARSE_C */
 }
 
 #if defined(MBEDTLS_FS_IO)
@@ -1353,6 +1357,14 @@
     p = buf;
     n = size;
 
+    if( NULL == crt )
+    {
+        ret = mbedtls_snprintf( p, n, "\nCertificate is uninitialised!\n" );
+        MBEDTLS_X509_SAFE_SNPRINTF;
+
+        return( (int) ( size - n ) );
+    }
+
     ret = mbedtls_snprintf( p, n, "%scert. version     : %d\n",
                                prefix, crt->version );
     MBEDTLS_X509_SAFE_SNPRINTF;