diff --git a/raco/expression/expression.py b/raco/expression/expression.py
index 376675c5..b206d9bf 100644
--- a/raco/expression/expression.py
+++ b/raco/expression/expression.py
@@ -350,14 +350,19 @@ def get_position(self, scheme, state_scheme=None):
 
 class UnnamedAttributeRef(AttributeRef):
 
-    def __init__(self, position):
+    def __init__(self, position, debug_info=None):
+        if debug_info is None:
+            debug_info = "${}".format(position)
+        self.debug_info = debug_info
         self.position = position
 
     def __str__(self):
-        return "$%s" % (self.position)
+        return "%s" % (self.debug_info)
 
     def __repr__(self):
-        return "{op}({pos!r})".format(op=self.opname(), pos=self.position)
+        return "{op}({pos!r}, {dbg!r})".format(op=self.opname(),
+                                               pos=self.position,
+                                               dbg=self.debug_info)
 
     def __eq__(self, other):
         return (other.__class__ == self.__class__
diff --git a/raco/myrial/groupby.py b/raco/myrial/groupby.py
index d1876380..f3f04c86 100644
--- a/raco/myrial/groupby.py
+++ b/raco/myrial/groupby.py
@@ -43,7 +43,7 @@ class NestedAggregateException(Exception):
     pass
 
 
-class InvalidAttributeRefException(Exception):
+class NonGroupedAccessException(Exception):
     '''Attempting to access a non-grouping term in an aggregate expression'''
     pass
 
@@ -73,7 +73,7 @@ def hoist_node(sexpr):
             # after the GroupBy
             input_pos = sexpr.get_position(input_scheme)
             if input_pos not in group_mappings:
-                raise InvalidAttributeRefException(str(sexpr))
+                raise NonGroupedAccessException(str(sexpr))
             output_pos = group_mappings[input_pos]
             return raco.expression.UnnamedAttributeRef(output_pos)
 
diff --git a/raco/myrial/multiway.py b/raco/myrial/multiway.py
index ad33f2f1..2608acee 100644
--- a/raco/myrial/multiway.py
+++ b/raco/myrial/multiway.py
@@ -15,6 +15,7 @@ def rewrite_node(sexpr):
             op = from_args[sexpr.relational_expression]
             scheme = op.scheme()
 
+            debug_info = None
             if not sexpr.field:
                 offset = 0
             elif isinstance(sexpr.field, int):
@@ -22,10 +23,12 @@ def rewrite_node(sexpr):
                     raise ColumnIndexOutOfBounds(str(sexpr))
                 offset = sexpr.field
             else:
+                assert isinstance(sexpr.field, basestring)
                 offset = scheme.getPosition(sexpr.field)
+                debug_info = sexpr.field
 
             offset += base_offsets[sexpr.relational_expression]
-            return expression.UnnamedAttributeRef(offset)
+            return expression.UnnamedAttributeRef(offset, debug_info)
 
     def recursive_eval(sexpr):
         """Rewrite a node and all its descendents"""
diff --git a/raco/myrial/query_tests.py b/raco/myrial/query_tests.py
index 673cb895..d1c69bff 100644
--- a/raco/myrial/query_tests.py
+++ b/raco/myrial/query_tests.py
@@ -911,7 +911,7 @@ def test_aggregate_illegal_colref(self):
         STORE(out, OUTPUT);
         """ % self.emp_key
 
-        with self.assertRaises(raco.myrial.groupby.InvalidAttributeRefException):  # noqa
+        with self.assertRaises(raco.myrial.groupby.NonGroupedAccessException):  # noqa
             self.check_result(query, None)
 
     def test_nested_aggregates_are_illegal(self):