diff --git a/dice/roller.py b/dice/roller.py
index 3a06f1e..f325d9c 100644
--- a/dice/roller.py
+++ b/dice/roller.py
@@ -64,7 +64,8 @@ class DiceRoller(object):
         up to a semicolon or end of line).
         """
         rolls = mods[0][0][1] if mods[0][0][1] else 1
-        assert trials <= 10, "Too many rolls (max: 10)."
+        if trials:
+            assert trials <= 10, "Too many rolls (max: 10)."
         assert rolls <= 50, "Too many dice (max: 50) in roll."
 
         output = ""