diff --git a/src/newgrf_optimiser.cpp b/src/newgrf_optimiser.cpp
index 16f5ca116c..b1e144fece 100644
--- a/src/newgrf_optimiser.cpp
+++ b/src/newgrf_optimiser.cpp
@@ -2230,7 +2230,6 @@ void OptimiseVarAction2DeterministicSpriteGroup(VarAction2OptimiseState &state,
 			}
 		}
 		group->default_group = target;
-		group->error_group = target;
 		group->ranges.clear();
 	}
 	if (!HasGrfOptimiserFlag(NGOF_NO_OPT_VARACT2_GROUP_PRUNE) && (state.inference & VA2AIF_ONE_OR_ZERO) && !group->calculated_result && group->ranges.size() == 1) {