diff --git a/src/mape/diskview.c b/src/mape/diskview.c
index 9afe4d823..13f61489f 100644
--- a/src/mape/diskview.c
+++ b/src/mape/diskview.c
@@ -136,7 +136,7 @@ static gboolean mape_disk_view_load_materials(MapeDiskView* disk_view,
 	gboolean overload_materials;
 	gboolean overload_textures;
 
-	/* Open Material.c4g group */
+	/* Open Material.ocg group */
 	gtk_tree_model_get(
 		disk_view->tree_store,
 		material_iter,
@@ -172,7 +172,7 @@ static gboolean mape_disk_view_load_materials(MapeDiskView* disk_view,
 		
 		group = mape_group_open_child(
 			parent_group,
-			"Material.c4g",
+			"Material.ocg",
 			error
 		);
 
@@ -199,7 +199,7 @@ static gboolean mape_disk_view_load_materials(MapeDiskView* disk_view,
 
 	if(overload_materials || overload_textures)
 	{
-		/* Look for overloaded Material.c4g */
+		/* Look for overloaded Material.ocg */
 		has_parent = gtk_tree_model_iter_parent(
 			disk_view->tree_store,
 			&parent_iter,
@@ -229,14 +229,14 @@ static gboolean mape_disk_view_load_materials(MapeDiskView* disk_view,
 				-1
 			);
 		
-			if(mape_group_has_entry(overloaded_group, "Material.c4g") ==
+			if(mape_group_has_entry(overloaded_group, "Material.ocg") ==
 				 TRUE)
 			{
 				/* TODO: Check if the group is already open!
 					 (mape_disk_view_find_iter). */
 				overloaded_group = mape_group_open_child(
 					overloaded_group,
-					"Material.c4g",
+					"Material.ocg",
 					error
 				);
 
@@ -455,7 +455,7 @@ static gboolean mape_disk_view_load(MapeDiskView* disk_view,
 		);
 
 		/* Create temporary entry to show the expander arrow */
-		if(g_strcasecmp(filename, "Material.c4g") != 0)
+		if(g_strcasecmp(filename, "Material.ocg") != 0)
 		{
 			gtk_tree_store_append(
 				GTK_TREE_STORE(disk_view->tree_store),
@@ -469,13 +469,13 @@ static gboolean mape_disk_view_load(MapeDiskView* disk_view,
 
 		if(fileext != NULL)
 		{
-			if(g_strcasecmp(fileext, ".c4d") == 0)
+			if(g_strcasecmp(fileext, ".ocd") == 0)
 				icon_type = MAPE_FILE_ICON_C4OBJECT;
-			else if(g_strcasecmp(fileext, ".c4f") == 0)
+			else if(g_strcasecmp(fileext, ".ocf") == 0)
 				icon_type = MAPE_FILE_ICON_C4FOLDER;
-			else if(g_strcasecmp(fileext, ".c4g") == 0)
+			else if(g_strcasecmp(fileext, ".ocg") == 0)
 				icon_type = MAPE_FILE_ICON_C4GROUP;
-			else if(g_strcasecmp(fileext, ".c4s") == 0)
+			else if(g_strcasecmp(fileext, ".ocs") == 0)
 				icon_type = MAPE_FILE_ICON_C4SCENARIO;
 		}
 
@@ -640,8 +640,8 @@ static gboolean mape_disk_view_cb_button_press_event(GtkWidget* widget,
 			-1
 		);
 
-		/* Load Material.c4g */
-		if(g_strcasecmp(filename, "Material.c4g") == 0)
+		/* Load Material.ocg */
+		if(g_strcasecmp(filename, "Material.ocg") == 0)
 		{
 			result = mape_disk_view_load_materials(
 				disk_view,
@@ -1092,7 +1092,7 @@ gboolean mape_disk_view_extend_to_path(MapeDiskView* disk_view,
 				return FALSE;
 			}
 
-			if(g_ascii_strcasecmp(file, "Material.c4g") == 0)
+			if(g_ascii_strcasecmp(file, "Material.ocg") == 0)
 			{
 				/* Assume end of path */
 				result = mape_disk_view_load_materials(
@@ -1132,7 +1132,7 @@ gboolean mape_disk_view_extend_to_path(MapeDiskView* disk_view,
 		}
 	}
 
-	/* All nodes expanded without opening Material.c4g */
+	/* All nodes expanded without opening Material.ocg */
 	g_strfreev(path_components);
 	return TRUE;
 }
diff --git a/src/mape/editview.c b/src/mape/editview.c
index 307f0ae99..b9de07d33 100644
--- a/src/mape/editview.c
+++ b/src/mape/editview.c
@@ -81,7 +81,7 @@ static GdkPixbuf* mape_edit_view_render_map(const gchar* source,
 			error,
 			g_quark_from_static_string("MAPE_EDIT_VIEW_ERROR"),
 			MAPE_EDIT_VIEW_ERROR_MISSING_MAPS,
-			"Material.c4g is not loaded"
+			"Material.ocg is not loaded"
 		);
 
 		return NULL;
diff --git a/src/mape/group.c b/src/mape/group.c
index cc480dfa5..cdd1864de 100644
--- a/src/mape/group.c
+++ b/src/mape/group.c
@@ -671,10 +671,10 @@ mape_group_is_child_folder(MapeGroup* group,
   ext = strrchr(child, '.');
   if(ext != NULL)
   {
-    if(g_ascii_strcasecmp(ext, ".c4s") == 0 ||
-       g_ascii_strcasecmp(ext, ".c4d") == 0 ||
-       g_ascii_strcasecmp(ext, ".c4f") == 0 ||
-       g_ascii_strcasecmp(ext, ".c4g") == 0)
+    if(g_ascii_strcasecmp(ext, ".o4s") == 0 ||
+       g_ascii_strcasecmp(ext, ".o4d") == 0 ||
+       g_ascii_strcasecmp(ext, ".o4f") == 0 ||
+       g_ascii_strcasecmp(ext, ".o4g") == 0)
    {
      return TRUE;
    }
diff --git a/src/mape/material.c b/src/mape/material.c
index 95e89eb52..1b0689661 100644
--- a/src/mape/material.c
+++ b/src/mape/material.c
@@ -23,7 +23,7 @@
  * @stability: Unstable
  *
  * #MapeMaterialMap is a simple GObject-based interface to C4MaterialMap.
- * It supports loading a material map from a Material.c4g group file. It can
+ * It supports loading a material map from a Material.ocg group file. It can
  * load multiple files, with newer entries overloading previous ones in case
  * of name clashes to support material overloading.
  **/
diff --git a/src/mape/window.c b/src/mape/window.c
index e2bc10797..f697b4691 100644
--- a/src/mape/window.c
+++ b/src/mape/window.c
@@ -537,7 +537,7 @@ MapeWindow* mape_window_new(int argc,
 	for(i = 1; i < argc; ++ i)
 	{
 		basename = g_path_get_basename(argv[i]);
-		if(g_strcasecmp(basename, "Material.c4g") == 0)
+		if(g_strcasecmp(basename, "Material.ocg") == 0)
 		{
 			if(!g_path_is_absolute(argv[i]))
 			{