diff --git a/src/voxels/WorldGenerator.hpp b/src/voxels/WorldGenerator.hpp
index 6f3f22fc..98cb955c 100644
--- a/src/voxels/WorldGenerator.hpp
+++ b/src/voxels/WorldGenerator.hpp
@@ -6,7 +6,7 @@
 
 struct voxel;
 class Content;
-class GeneratorDef;
+struct GeneratorDef;
 
 class WorldGenerator {
     const GeneratorDef& def;