diff --git a/ckanext/datesearch/plugin.py b/ckanext/datesearch/plugin.py
index a641d1f..a4aefff 100644
--- a/ckanext/datesearch/plugin.py
+++ b/ckanext/datesearch/plugin.py
@@ -27,16 +27,19 @@ class DateSearchPlugin(plugins.SingletonPlugin):
         end_date = extras.get('ext_enddate')
         log.debug("end_date: {0}".format(end_date))
 
-        if not start_date or not end_date:
-            # The user didn't select a start and end date, so do nothing.
+        if not start_date and not end_date:
+            # The user didn't select either a start and/or end date, so do nothing.
             return search_params
+        if not start_date:
+            start_date = '*'
+        if not end_date:
+            end_date = '*'
 
-        # Add a date-range query with the selected start and end dates into the
-        # Solr facet queries.
+        # Add a date-range query with the selected start and/or end dates into the Solr facet queries.
         fq = search_params['fq']
         log.debug("fq: {0}".format(fq))
-        fq = '{fq} +metadata_modified:[{start_date} TO {end_date}]'.format(
-            fq=fq, start_date=start_date, end_date=end_date)
+        fq = '{fq} +metadata_modified:[{sd} TO {ed}]'.format(fq=fq, sd=start_date, ed=end_date)
+
         log.debug("fq: {0}".format(fq))
         search_params['fq'] = fq
         log.debug("search_params: {0}".format(search_params))