--- a/conserver/cutil.h
+++ b/conserver/cutil.h
@@ -7,6 +7,8 @@
 #include <stdarg.h>
 #if HAVE_OPENSSL
 # include <openssl/ssl.h>
+# include <openssl/bn.h>
+# include <openssl/dh.h>
 # include <openssl/err.h>
 # if OPENSSL_VERSION_NUMBER < 0x10100000L
 #  define TLS_method SSLv23_method