diff --git a/src/resourcefiles/resourcefile.cpp b/src/resourcefiles/resourcefile.cpp
index bf82911d7..02271a65b 100644
--- a/src/resourcefiles/resourcefile.cpp
+++ b/src/resourcefiles/resourcefile.cpp
@@ -131,7 +131,7 @@ void FResourceLump::LumpNameSetup(FString iname)
 	// Since '\' can't be used as a file name's part inside a ZIP
 	// we have to work around this for sprites because it is a valid
 	// frame character.
-	else if (Namespace == ns_sprites || Namespace == ns_voxels)
+	else if (Namespace == ns_sprites || Namespace == ns_voxels || Namespace == ns_hires)
 	{
 		char *c;