diff --git a/lib/isc/include/isc/commandline.h b/lib/isc/include/isc/commandline.h
index dfa8430d3f..a7895a800f 100644
--- a/lib/isc/include/isc/commandline.h
+++ b/lib/isc/include/isc/commandline.h
@@ -18,6 +18,7 @@
 #include <limits.h>
 #include <stdbool.h>
 
+#include <isc/dir.h>
 #include <isc/result.h>
 #include <isc/types.h>