diff --git a/layouts/partials/site-sidebar.de.html b/layouts/partials/site-sidebar.de.html
index 0332528..386abb2 100644
--- a/layouts/partials/site-sidebar.de.html
+++ b/layouts/partials/site-sidebar.de.html
@@ -62,7 +62,7 @@ Offen bis {{ .cfp_end_date_day }}. {{ i18n .cfp_end_date_month }} {{ .date_year
 {{ end }}
 
 
-<p><strong>IRC:</strong> <a href="{{ .irc_server | safeURL }}{{ .irc_channel }}">{{ .irc_channel }}</a></p>
+<p><strong><s>IRC:</s></strong> <a href="{{ .irc_server | safeURL }}{{ .irc_channel }}"><s>{{ .irc_channel }}</s></a> (obsolet)</p>
 
 
 <p><strong>Matrix:</strong> <a href="{{ .matrix_client | safeURL }}{{ urlquery .matrix_room }}:{{ .matrix_server }}">{{ .matrix_room }}:{{ .matrix_server }}</a></p>
diff --git a/layouts/partials/site-sidebar.en.html b/layouts/partials/site-sidebar.en.html
index bafd126..476951f 100644
--- a/layouts/partials/site-sidebar.en.html
+++ b/layouts/partials/site-sidebar.en.html
@@ -62,7 +62,7 @@ Open until {{ .cfp_end_date_day }}. {{ i18n .cfp_end_date_month }} {{ .date_year
 {{ end }}
 
 
-<p><strong>IRC:</strong> <a href="{{ .irc_server | safeURL }}{{ .irc_channel }}">{{ .irc_channel }}</a></p>
+<p><strong><s>IRC:</s></strong> <a href="{{ .irc_server | safeURL }}{{ .irc_channel }}"><s>{{ .irc_channel }}</s></a> (obsolete)</p>
 
 
 <p><strong>Matrix:</strong> <a href="{{ .matrix_client | safeURL }}{{ urlquery .matrix_room }}:{{ .matrix_server }}">{{ .matrix_room }}:{{ .matrix_server }}</a></p>
diff --git a/layouts/partials/site-sidebar.fr.html b/layouts/partials/site-sidebar.fr.html
index 5fb30c3..09f9fef 100644
--- a/layouts/partials/site-sidebar.fr.html
+++ b/layouts/partials/site-sidebar.fr.html
@@ -62,7 +62,7 @@ Offen bis {{ .cfp_end_date_day }}. {{ i18n .cfp_end_date_month }} {{ .date_year
 {{ end }}
 
 
-<p><strong>IRC:</strong> <a href="{{ .irc_server | safeURL }}{{ .irc_channel }}">{{ .irc_channel }}</a></p>
+<p><strong><s>IRC:</s></strong> <a href="{{ .irc_server | safeURL }}{{ .irc_channel }}"><s>{{ .irc_channel }}</s></a> (obsolète)</p>
 
 
 <p><strong>Matrix:</strong> <a href="{{ .matrix_client | safeURL }}{{ urlquery .matrix_room }}:{{ .matrix_server }}">{{ .matrix_room }}:{{ .matrix_server }}</a></p>
diff --git a/layouts/partials/site-sidebar.it.html b/layouts/partials/site-sidebar.it.html
index 9c9a28e..b604acd 100644
--- a/layouts/partials/site-sidebar.it.html
+++ b/layouts/partials/site-sidebar.it.html
@@ -62,7 +62,7 @@ Offen bis {{ .cfp_end_date_day }}. {{ i18n .cfp_end_date_month }} {{ .date_year
 {{ end }}
 
 
-<p><strong>IRC:</strong> <a href="{{ .irc_server | safeURL }}{{ .irc_channel }}">{{ .irc_channel }}</a></p>
+<p><strong><s>IRC:</s></strong> <a href="{{ .irc_server | safeURL }}{{ .irc_channel }}"><s>{{ .irc_channel }}</s></a> (obsoleto)</p>
 
 
 <p><strong>Matrix:</strong> <a href="{{ .matrix_client | safeURL }}{{ urlquery .matrix_room }}:{{ .matrix_server }}">{{ .matrix_room }}:{{ .matrix_server }}</a></p>