diff --git a/lib/isc/commandline.c b/lib/isc/commandline.c
index 4e18730033..fdbcbb46e3 100644
--- a/lib/isc/commandline.c
+++ b/lib/isc/commandline.c
@@ -47,9 +47,9 @@
  * and format in the ISC coding style.
  */
 
+#include <limits.h>
 #include <stdbool.h>
 #include <stdio.h>
-#include <zconf.h>
 
 #include <isc/commandline.h>
 #include <isc/file.h>
diff --git a/lib/isc/include/isc/commandline.h b/lib/isc/include/isc/commandline.h
index c0d226ddcc..dfa8430d3f 100644
--- a/lib/isc/include/isc/commandline.h
+++ b/lib/isc/include/isc/commandline.h
@@ -15,8 +15,8 @@
 
 /*! \file isc/commandline.h */
 
+#include <limits.h>
 #include <stdbool.h>
-#include <zconf.h>
 
 #include <isc/result.h>
 #include <isc/types.h>