diff --git a/ckanext/datesearch/plugin.py b/ckanext/datesearch/plugin.py
index e819afa..caaa484 100644
--- a/ckanext/datesearch/plugin.py
+++ b/ckanext/datesearch/plugin.py
@@ -33,7 +33,7 @@ class DateSearchPlugin(plugins.SingletonPlugin):
             end_date = '*'
 
         # Add a date-range query with the selected start and/or end dates into the Solr facet queries.
-        fq = search_params['fq']
+        fq = search_params.get('fq', '')
         fq = '{fq} +extras_PublicationTimestamp:[{sd} TO {ed}]'.format(fq=fq, sd=start_date, ed=end_date)
 
         search_params['fq'] = fq