diff --git a/similar/3d/interp.cpp b/similar/3d/interp.cpp
index 80758e6f3..c0629986f 100644
--- a/similar/3d/interp.cpp
+++ b/similar/3d/interp.cpp
@@ -493,6 +493,7 @@ public:
 	}
 };
 
+constexpr glow_num_stub g3_draw_morphing_model_state::glow_num;
 constexpr const glow_values_t *g3_draw_morphing_model_state::glow_values;
 
 }