diff --git a/programs/x509/cert_app.c b/programs/x509/cert_app.c
index 51d71aef2..3d175281a 100644
--- a/programs/x509/cert_app.c
+++ b/programs/x509/cert_app.c
@@ -55,6 +55,7 @@ int main( void )
 #include "polarssl/net.h"
 #include "polarssl/ssl.h"
 #include "polarssl/x509.h"
+#include "polarssl/debug.h"
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -375,6 +376,10 @@ int main( int argc, char *argv[] )
 
         polarssl_printf( " ok\n" );
 
+#if defined(POLARSSL_DEBUG_C)
+        debug_set_threshold( opt.debug_level );
+#endif
+
         /*
          * 2. Start the connection
          */