diff --git a/COFF/PDB.cpp b/COFF/PDB.cpp
index 43714e6..8d42f78 100644
--- a/COFF/PDB.cpp
+++ b/COFF/PDB.cpp
@@ -1058,7 +1058,7 @@
 
     default:
       warn("ignoring unknown debug$S subsection kind 0x" +
-           utohexstr(uint32_t(SS.kind())));
+           utohexstr(uint32_t(SS.kind())) + " in file " + toString(&File));
       break;
     }
   }