diff --git a/Lib/fontTools/mtiLib/__init__.py b/Lib/fontTools/mtiLib/__init__.py
index 97b91ea1c..2ec710131 100644
--- a/Lib/fontTools/mtiLib/__init__.py
+++ b/Lib/fontTools/mtiLib/__init__.py
@@ -12,6 +12,8 @@ from fontTools.ttLib.tables import otTables as ot
 from fontTools.ttLib.tables.otBase import ValueRecord, valueRecordFormatDict
 from fontTools.otlLib import builder as otl
 from contextlib import contextmanager
+from fontTools.ttLib import newTable
+from fontTools.feaLib.lookupDebugInfo import LOOKUP_DEBUG_INFO_KEY
 from operator import setitem
 import logging
 
@@ -1036,7 +1038,13 @@ def parseGSUBGPOS(lines, font, tableTag):
         self.LookupList.LookupCount = len(self.LookupList.Lookup)
     if lookupMap is not None:
         lookupMap.applyDeferredMappings()
-    if featureMap is not None:
+        if "Debg" not in font:
+            font["Debg"] = newTable("Debg")
+            font["Debg"].data = {}
+        debug = font["Debg"].data.setdefault(LOOKUP_DEBUG_INFO_KEY, {}).setdefault(tableTag, {})
+        for name, lookup in lookupMap.items():
+            debug[str(lookup)] = ["", name, ""]
+
         featureMap.applyDeferredMappings()
     container.table = self
     return container