diff --git a/monasca_api/v2/reference/alarms.py b/monasca_api/v2/reference/alarms.py
index 5620add98..832375e73 100644
--- a/monasca_api/v2/reference/alarms.py
+++ b/monasca_api/v2/reference/alarms.py
@@ -383,7 +383,10 @@ class AlarmsStateHistory(alarms_api_v2.AlarmsStateHistoryV2API,
 
         # get_alarms expects 'metric_dimensions' for dimensions key.
         if 'dimensions' in query_parms:
-            new_query_parms = {'metric_dimensions': query_parms['dimensions']}
+            dimensions = query_parms['dimensions']
+            if not isinstance(dimensions, list):
+                dimensions = [dimensions]
+            new_query_parms = {'metric_dimensions': dimensions}
         else:
             new_query_parms = {}