diff --git a/programs/x509/cert_app.c b/programs/x509/cert_app.c
index 0c632ba..1ded9dd 100644
--- a/programs/x509/cert_app.c
+++ b/programs/x509/cert_app.c
@@ -31,6 +31,8 @@
 #include <stdlib.h>
 #include <stdio.h>
 
+#include "polarssl/config.h"
+
 #include "polarssl/havege.h"
 #include "polarssl/net.h"
 #include "polarssl/ssl.h"
@@ -77,6 +79,19 @@
     "    debug_level=%%d      default: 0 (disabled)\n"  \
     "\n"
 
+#if !defined(POLARSSL_BIGNUM_C) || !defined(POLARSSL_HAVEGE_C) ||   \
+    !defined(POLARSSL_SSL_TLS_C) || !defined(POLARSSL_SSL_CLI_C) || \
+    !defined(POLARSSL_NET_C) || !defined(POLARSSL_RSA_C) ||         \
+    !defined(POLARSSL_X509_PARSE_C) || !defined(POLARSSL_FS_IO)
+int main( void )
+{
+    printf("POLARSSL_BIGNUM_C and/or POLARSSL_HAVEGE_C and/or "
+           "POLARSSL_SSL_TLS_C and/or POLARSSL_SSL_CLI_C and/or "
+           "POLARSSL_NET_C and/or POLARSSL_RSA_C and/or "
+           "POLARSSL_X509_PARSE_C and/or POLARSSL_FS_IO not defined.\n");
+    return( 0 );
+}
+#else
 int main( int argc, char *argv[] )
 {
     int ret = 0, server_fd;
@@ -287,3 +302,6 @@
 
     return( ret );
 }
+#endif /* POLARSSL_BIGNUM_C && POLARSSL_HAVEGE_C && POLARSSL_SSL_TLS_C &&
+          POLARSSL_SSL_CLI_C && POLARSSL_NET_C && POLARSSL_RSA_C &&
+          POLARSSL_X509_PARSE_C && POLARSSL_FS_IO */