diff --git a/README b/README
index 06769d0f1117255ddf6894cda4816c702b356b2a..658b3d8252a34e6a37d474a0d65986ed61a02974 100644
--- a/README
+++ b/README
@@ -11,6 +11,7 @@ Knot DNS has several dependencies:
 
 Optional packages:
 * libcap-ng >= 0.6.4 (for POSIX 1003.1e capabilites(7))
+* libidn             (for IDNA2003 support in Knot utilities)
 
 Dependencies for building documentation:
 * texinfo
diff --git a/man/kdig.1.in b/man/kdig.1.in
index f7fc0e887fd9c3473b1b6dbb110e49c38feab7e8..9f2db71ed812af035a8ab4a1bed82018694e041f 100644
--- a/man/kdig.1.in
+++ b/man/kdig.1.in
@@ -164,7 +164,7 @@ Use EDNS version (default is 0).
 .TP
 .BR +noidn
 Disable IDN transformation to ASCII and vice versa.
-IDN support depends on libidn availability during project building!
+IDNA2003 support depends on libidn availability during project building!
 .TP
 .BI +time= T
 Set wait for reply interval in seconds (default is 5 seconds).