1 files changed, 13 insertions, 1 deletions
diff --git a/scene/3d/mesh_instance_3d.cpp b/scene/3d/mesh_instance_3d.cpp
index 88b1c340d8..16de95bfb1 100644
--- a/scene/3d/mesh_instance_3d.cpp
+++ b/scene/3d/mesh_instance_3d.cpp
@@ -52,7 +52,19 @@ bool MeshInstance3D::_set(const StringName &p_name, const Variant &p_value) {
 
 	if (p_name.operator String().begins_with("surface_material_override/")) {
 		int idx = p_name.operator String().get_slicec('/', 1).to_int();
-		if (idx >= surface_override_materials.size() || idx < 0) {
+
+		// This is a bit of a hack to ensure compatibility with material
+		// overrides that start indexing at 1.
+		// We assume that idx 0 is always read first, if its not, this won't work.
+		if (idx == 0) {
+			surface_index_0 = true;
+		}
+		if (!surface_index_0) {
+			// This means the file was created when the indexing started at 1, so decrease by one.
+			idx--;
+		}
+
+		if (idx > surface_override_materials.size() || idx < 0) {
 			return false;
 		}