diff --git a/Makefile b/Makefile
index abe9b51d5..e4839e1c9 100644
--- a/Makefile
+++ b/Makefile
@@ -64,7 +64,7 @@ NEWSFILES:=build/news.html build/news-rss.xml build/news-atom.xml \
 	build/news-archiv-rss.xml build/news-archiv-atom.xml \
 	build/podcast-archiv.xml build/pentaradio-archiv.xml build/pentacast-archiv.xml \
 	build/pentamusic-archiv.xml build/pentamedia-archiv.xml \
-	build/ical.ics build/xcal.xml build/reminders \
+	build/ical.ics build/gchq.ics build/xcal.xml build/reminders \
 	build/datenspuren/$(DS_YEAR)/news-rss.xml build/datenspuren/$(DS_YEAR)/news-atom.xml \
 	build/pentacast-ogg.xml build/pentacast-ogg-archiv.xml \
 	build/portal.html
@@ -209,6 +209,15 @@ build/ical.ics : VFLAGS_OUT=$(VFLAGS)
 build/ical.ics: $(CALENDAR_SUMMARY) $(STYLE)
 	$(call xml_process)
 
+# iCal with events at GCHQ, for http://itedd.de/
+build/gchq.ics : STYLE=xsl/ical.xsl
+build/gchq.ics : PFLAGS+=--stringparam location-filter GCHQ
+build/gchq.ics : NOVALID:=true
+build/gchq.ics : VFLAGS_IN=$(VFLAGS)
+build/gchq.ics : VFLAGS_OUT=$(VFLAGS)
+build/gchq.ics: $(CALENDAR_SUMMARY) $(STYLE)
+	$(call xml_process)
+
 # Remind
 build/reminders : STYLE=xsl/remind.xsl
 build/reminders : NOVALID:=true
diff --git a/xsl/ical.xsl b/xsl/ical.xsl
index 5cdc42a1f..65b8af9c8 100644
--- a/xsl/ical.xsl
+++ b/xsl/ical.xsl
@@ -8,6 +8,7 @@
 
   <xsl:include href="common.xsl"/>
 
+  <xsl:param name="location-filter"/>
   <xsl:variable name="baseurl">https://www.c3d2.de/</xsl:variable>
 
   <!-- A week ago -->
@@ -45,26 +46,27 @@
     <xsl:for-each select="event[starts-with(date:difference(start, $minstart), '-')]">
       <xsl:sort select="date:seconds(@start)" data-type="number" order="descending" />
 
-      <xsl:text>&#13;&#10;</xsl:text>
-      <xsl:text>BEGIN:VEVENT</xsl:text>
-      <xsl:text>&#13;&#10;</xsl:text>
+      <xsl:if test="contains(location, $location-filter)">
+        <xsl:text>&#13;&#10;</xsl:text>
+        <xsl:text>BEGIN:VEVENT</xsl:text>
+        <xsl:text>&#13;&#10;</xsl:text>
 
-      <xsl:text>METHOD:PUBLISH</xsl:text>
-      <xsl:text>&#13;&#10;</xsl:text>
+        <xsl:text>METHOD:PUBLISH</xsl:text>
+        <xsl:text>&#13;&#10;</xsl:text>
 
-      <xsl:call-template name="uid"/>
-      <xsl:apply-templates select="start"/>
-      <xsl:apply-templates select="end"/>
-      <xsl:apply-templates select="title"/>
-      <xsl:text>CLASS:PUBLIC</xsl:text>
-      <xsl:text>&#13;&#10;</xsl:text>
-      <xsl:call-template name="category"/>
-      <xsl:apply-templates select="link"/>
-      <xsl:apply-templates select="location"/>
-
-      <xsl:text>END:VEVENT</xsl:text>
-      <xsl:text>&#13;&#10;</xsl:text>
+        <xsl:call-template name="uid"/>
+        <xsl:apply-templates select="start"/>
+        <xsl:apply-templates select="end"/>
+        <xsl:apply-templates select="title"/>
+        <xsl:text>CLASS:PUBLIC</xsl:text>
+        <xsl:text>&#13;&#10;</xsl:text>
+        <xsl:call-template name="category"/>
+        <xsl:apply-templates select="link"/>
+        <xsl:apply-templates select="location"/>
 
+        <xsl:text>END:VEVENT</xsl:text>
+        <xsl:text>&#13;&#10;</xsl:text>
+      </xsl:if>
     </xsl:for-each>
 
     <xsl:text>&#13;&#10;</xsl:text>