diff --git a/vncviewer/CConn.cxx b/vncviewer/CConn.cxx
index 6f6a21a..d69cd4e 100644
--- a/vncviewer/CConn.cxx
+++ b/vncviewer/CConn.cxx
@@ -17,6 +17,10 @@
  * USA.
  */
 
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
 #include <assert.h>
 #ifndef _WIN32
 #include <unistd.h>