diff --git a/grudge/function_registry.py b/grudge/function_registry.py
index df709f93e7ab13fd180d91cca0cce30735ae8f87..31961b6f48a26183b09c6673e04e860eeb7128d1 100644
--- a/grudge/function_registry.py
+++ b/grudge/function_registry.py
@@ -88,6 +88,7 @@ class CElementwiseUnaryFunction(Function):
         i = Variable("i")
 
         if self.identifier == "fabs":  # FIXME
+            # Loopy has a type-adaptive "abs", but no "fabs".
             func_name = "abs"
 
         cached_name += func_name