diff --git a/common/rfb/SSecurityVeNCrypt.h b/common/rfb/SSecurityVeNCrypt.h
index 526dad1..bedb6e2 100644
--- a/common/rfb/SSecurityVeNCrypt.h
+++ b/common/rfb/SSecurityVeNCrypt.h
@@ -25,6 +25,14 @@
 #ifndef __SSECURITYVENCRYPT_H__
 #define __SSECURITYVENCRYPT_H__
 
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#ifndef HAVE_GNUTLS
+#error "This header should not be included without HAVE_GNUTLS defined"
+#endif
+
 #include <rfb/SSecurityStack.h>
 #include <rfb/SConnection.h>