diff --git a/pyiso/base.py b/pyiso/base.py
index 50b1ef7..056b9e4 100644
--- a/pyiso/base.py
+++ b/pyiso/base.py
@@ -28,7 +28,7 @@ class BaseClient(object):
     logger = logging.getLogger(__name__)
 
     # choices for market and frequency interval labels
-    MARKET_CHOICES = IntervalChoices(hourly='RTHR', fivemin='RT5M', tenmin='RT5M', na='RT5M', dam='DAM')
+    MARKET_CHOICES = IntervalChoices(hourly='RTHR', fivemin='RT5M', tenmin='RT5M', na='RT5M', dam='DAHR')
     FREQUENCY_CHOICES = IntervalChoices(hourly='1hr', fivemin='5m', tenmin='10m', na='n/a', dam='1hr')
 
     # timezone
diff --git a/tests/test_base.py b/tests/test_base.py
index 0a48c23..a0c384d 100644
--- a/tests/test_base.py
+++ b/tests/test_base.py
@@ -30,7 +30,7 @@ def test_market_choices(self):
 
         self.assertEqual('RTHR', bc.MARKET_CHOICES.hourly)
         self.assertEqual('RT5M', bc.MARKET_CHOICES.fivemin)
-        self.assertEqual('DAM', bc.MARKET_CHOICES.dam)
+        self.assertEqual('DAHR', bc.MARKET_CHOICES.dam)
 
     def test_freq_choices(self):
         """Frequency choices have expected values."""