diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index b78eebd720..4a4dacf4c8 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -1,4 +1,6 @@
 
+#include <config.h>
+
 #include <isc/assertions.h>
 #include <isc/result.h>
 #include <isc/timer.h>