diff --git a/config.h.cmake.in b/config.h.cmake.in
index 18a5e1c..27e90c4 100644
--- a/config.h.cmake.in
+++ b/config.h.cmake.in
@@ -11,6 +11,7 @@
 #cmakedefine HAVE_GNUTLS_DATUM_T
 #cmakedefine HAVE_GNUTLS_PK_ALGORITHM_T
 #cmakedefine HAVE_GNUTLS_SIGN_ALGORITHM_T
+#cmakedefine HAVE_FLTK_DEAD_KEYS
 
 /* MS Visual Studio 2008 and newer doesn't know ssize_t */
 #if defined(HAVE_GNUTLS) && defined(WIN32) && !defined(__MINGW32__)