diff --git a/sandbox/grist/codebuilder.py b/sandbox/grist/codebuilder.py
index 3466a278..ca5324d2 100644
--- a/sandbox/grist/codebuilder.py
+++ b/sandbox/grist/codebuilder.py
@@ -350,7 +350,8 @@ def parse_grist_names(builder):
     if not patch_source:
       return None
     in_text, in_value, in_patch = patch_source
-    return (in_value, in_patch.start, table_id, col_id)
+    if in_value:
+      return (in_value, in_patch.start, table_id, col_id)
 
   parsed_names = []
   for node in asttokens.util.walk(atok.tree):
diff --git a/sandbox/grist/gencode.py b/sandbox/grist/gencode.py
index e922afd0..65f5ed7d 100644
--- a/sandbox/grist/gencode.py
+++ b/sandbox/grist/gencode.py
@@ -92,7 +92,10 @@ class GenCode(object):
     body = self._formula_cache.get(key)
     if body is None:
       default = get_type_default(col_info.type)
-      body = codebuilder.make_formula_body(col_info.formula, default, (table_id, col_info.colId))
+      # If we have a table_id like `Table._Summary`, then we don't want to actually associate
+      # this field with any real table/column.
+      assoc_value = None if table_id.endswith("._Summary") else (table_id, col_info.colId)
+      body = codebuilder.make_formula_body(col_info.formula, default, assoc_value)
     self._new_formula_cache[key] = body
 
     decorator = ''
@@ -147,7 +150,12 @@ class GenCode(object):
                              for c in six.itervalues(s.columns) if c.isFormula)
       parts.append(indent(textbuilder.Text("\nclass _Summary:\n")))
       for col_info in six.itervalues(formulas):
-        parts.append(indent(self._make_field(col_info, table_id), levels=2))
+        # Associate this field with the fake table `table_id + "._Summary"`.
+        # We don't know which summary table each formula belongs to, there might be several,
+        # and we don't care here because this is just for display in the code view.
+        # The real formula will be associated with the real summary table elsewhere.
+        # Previously this field was accidentally associated with the source table, causing bugs.
+        parts.append(indent(self._make_field(col_info, table_id + "._Summary"), levels=2))
 
     return textbuilder.Combiner(parts)
 
diff --git a/sandbox/grist/test_summary.py b/sandbox/grist/test_summary.py
index 2a0a58ed..d8d0601b 100644
--- a/sandbox/grist/test_summary.py
+++ b/sandbox/grist/test_summary.py
@@ -529,6 +529,13 @@ class Address:
       [2, "Address_summary_city_state",   1],
     ])
 
+    # Add a column to the summary table with a name that doesn't exist in the source table,
+    # to test a specific bug fix.
+    self.add_column(
+      "Address_summary_city_state", "lookup",
+      formula="Address.lookupRecords(city=$city)", isFormula=True
+    )
+
     # Rename the table: this is what we are really testing in this test case.
     self.apply_user_action(["RenameTable", "Address", "Location"])
 
@@ -537,6 +544,14 @@ class Address:
       [2, "Location_summary_city_state",   1],
     ])
 
+    # Check that the summary table column's formula was updated correctly.
+    self.assertTableData("_grist_Tables_column", cols="subset", rows="subset", data=[
+      ["id", "colId", "formula"],
+      [19, "lookup", "Location.lookupRecords(city=$city)"],
+    ])
+    # This column isn't expected in _do_test_updates().
+    self.remove_column("Location_summary_city_state", "lookup")
+
     # Verify that the bigger summary table respects all updates to the renamed source table.
     self._do_test_updates("Location", "Location_summary_city_state")