diff --git a/similar/main/polyobj.cpp b/similar/main/polyobj.cpp
index e068ebafc..a9d9a28ce 100644
--- a/similar/main/polyobj.cpp
+++ b/similar/main/polyobj.cpp
@@ -766,9 +766,9 @@ void polygon_model_data_read(polymodel *pm, PHYSFS_File *fp)
 	if (words_bigendian)
 	swap_polygon_model_data(pm->model_data.get());
 #if defined(DXX_BUILD_DESCENT_I)
-	g3_validate_polygon_model(pm->model_data.get(), model_data_size);
+	g3_validate_polygon_model(pm->model_data.get(), pm->model_data_size);
 #elif defined(DXX_BUILD_DESCENT_II)
-	g3_init_polygon_model(pm->model_data.get(), model_data_size);
+	g3_init_polygon_model(pm->model_data.get(), pm->model_data_size);
 #endif
 }
 }