diff --git a/src/d_main.cpp b/src/d_main.cpp
index e1adfe025..a00a3f06c 100644
--- a/src/d_main.cpp
+++ b/src/d_main.cpp
@@ -198,7 +198,7 @@ extern bool insave;
 extern TDeletingArray<FLightDefaults *> LightDefaults;
 extern FName MessageBoxClass;
 
-const char* iwad_folders[13] = { "flats/", "textures/", "hires/", "sprites/", "voxels/", "colormaps/", "acs/", "maps/", "voices/", "patches/", "graphics/", "sounds/", "music/" };
+const char* iwad_folders[13] = { "flats/", "textures/", "hires/", "sprites/", "voxels/", "colormaps/", "acs/", "maps/", "voices/", "patches/", "graphics/", "sounds/", "music/", "materials/"};
 const char* iwad_reserved[12] = { "mapinfo", "zmapinfo", "gameinfo", "sndinfo", "sbarinfo", "menudef", "gldefs", "animdefs", "decorate", "zscript", "iwadinfo", "maps/" };