diff --git a/lib/hx509/hx_locl.h b/lib/hx509/hx_locl.h
index 3eceee32e..3b1238dec 100644
--- a/lib/hx509/hx_locl.h
+++ b/lib/hx509/hx_locl.h
@@ -50,6 +50,7 @@
 #include <hex.h>
 #include <roken.h>
 #include <com_err.h>
+#include <parse_units.h>
 
 #include <krb5-types.h>