diff --git a/config.h.in b/config.h.in
index 17d2aedd17..15305b143f 100644
--- a/config.h.in
+++ b/config.h.in
@@ -229,7 +229,7 @@ int sigwait(const unsigned int *set, int *sig);
 /* Define to 1 if you have the <gssapi_krb5.h> header file. */
 #undef HAVE_GSSAPI_KRB5_H
 
-/* Define to 1 if you have the `if_nametoindex' function. */
+/* Define to 1 if you have the if_nametoindex function. */
 #undef HAVE_IF_NAMETOINDEX
 
 /* Define to 1 if you have the <inttypes.h> header file. */
diff --git a/configure.in b/configure.in
index f36af42bad..fb91e682f9 100644
--- a/configure.in
+++ b/configure.in
@@ -2886,7 +2886,9 @@ esac
 case $ac_cv_have_if_nametoindex in
 yes)
 	ISC_PLATFORM_HAVEIFNAMETOINDEX="#define ISC_PLATFORM_HAVEIFNAMETOINDEX 1"
-	AC_DEFINE(HAVE_IF_NAMETOINDEX, 1)
+        AC_DEFINE(HAVE_IF_NAMETOINDEX, 1,
+                  [Define to 1 if you have the if_nametoindex function.])
+
 	;;
 *)
 	ISC_PLATFORM_HAVEIFNAMETOINDEX="#undef ISC_PLATFORM_HAVEIFNAMETOINDEX"