diff --git a/src/Time/sunsolver.cxx b/src/Time/sunsolver.cxx
index c9bd04efe..fdf616e4b 100644
--- a/src/Time/sunsolver.cxx
+++ b/src/Time/sunsolver.cxx
@@ -23,6 +23,10 @@
  * $Id$
  */
 
+#ifdef HAVE_CONFIG_H
+#      include <config.h>
+#endif
+
 #ifdef SG_HAVE_STD_INCLUDES
 #  include <cmath>
 // #  include <cstdio>