diff --git a/src/humulus/filters.py b/src/humulus/filters.py
index 5c12f81..cf178d4 100644
--- a/src/humulus/filters.py
+++ b/src/humulus/filters.py
@@ -83,6 +83,8 @@ def recipe_ibu_ratio(recipe):
     """Return a recipe's IBU ratio"""
     if 'fermentables' not in recipe or 'hops' not in recipe:
         return '0'
+    if len(recipe['fermentables']) == 0:
+        return '0'  # Otherwise a divide by zero error will occur
     og = float(recipe_og(recipe))
     ibu = float(recipe_ibu(recipe))
     return '{:.2f}'.format(round(0.001 * ibu / (og - 1), 2))