diff --git a/calendar/resources/content/calendarImportExport.js b/calendar/resources/content/calendarImportExport.js
index 88f432a17b1..734c4640b7a 100644
--- a/calendar/resources/content/calendarImportExport.js
+++ b/calendar/resources/content/calendarImportExport.js
@@ -67,7 +67,7 @@ const extensionCsv      = ".csv";
 const filterRdf         = "iCalendar RDF";
 const extensionRdf      = ".rdf";
 
-if( opener.gICalLib )
+if( opener && opener.gICalLib )
    gICalLib = opener.gICalLib;
 
 // convert to and from Unicode for file i/o
diff --git a/calendar/resources/content/importExport.js b/calendar/resources/content/importExport.js
index 88f432a17b1..734c4640b7a 100644
--- a/calendar/resources/content/importExport.js
+++ b/calendar/resources/content/importExport.js
@@ -67,7 +67,7 @@ const extensionCsv      = ".csv";
 const filterRdf         = "iCalendar RDF";
 const extensionRdf      = ".rdf";
 
-if( opener.gICalLib )
+if( opener && opener.gICalLib )
    gICalLib = opener.gICalLib;
 
 // convert to and from Unicode for file i/o