diff --git a/src/r_data/gldefs.cpp b/src/r_data/gldefs.cpp
index 345bad544b9..4f5dc46597d 100644
--- a/src/r_data/gldefs.cpp
+++ b/src/r_data/gldefs.cpp
@@ -1155,7 +1155,7 @@ class GLDefsParser
 			if (lumpnum != -1)
 			{
 				if (iwad && fileSystem.GetFileContainer(lumpnum) <= fileSystem.GetMaxIwadNum()) useme = true;
-				if (thiswad && fileSystem.GetFileContainer(lumpnum) == workingLump) useme = true;
+				if (thiswad && fileSystem.GetFileContainer(lumpnum) == fileSystem.GetFileContainer(workingLump)) useme = true;
 			}
 			if (!useme) return;
 		}