diff --git a/src/meshlabplugins/filter_trioptimize/filter_trioptimize.cpp b/src/meshlabplugins/filter_trioptimize/filter_trioptimize.cpp
index 371918597..d8801ac65 100644
--- a/src/meshlabplugins/filter_trioptimize/filter_trioptimize.cpp
+++ b/src/meshlabplugins/filter_trioptimize/filter_trioptimize.cpp
@@ -130,6 +130,7 @@ TriOptimizePlugin::TriOptimizePlugin()
 		case FP_NEAR_LAPLACIAN_SMOOTH: 	return tr("Laplacian Smooth (surface preserving)");
 		default:		assert(0);
 	}
+	return {};
 }
 
  int TriOptimizePlugin::getRequirements(QAction *action)
@@ -162,6 +163,7 @@ TriOptimizePlugin::TriOptimizePlugin()
 					   "on original surface");
 		default : assert(0);
 	}
+	return {};
 }
 
  TriOptimizePlugin::FilterClass TriOptimizePlugin::getClass(QAction *action)
@@ -183,6 +185,7 @@ int TriOptimizePlugin::postCondition(QAction *a) const
 		case FP_NEAR_LAPLACIAN_SMOOTH : return MeshModel::MM_VERTCOORD | MeshModel::MM_VERTNORMAL;
 		default                       : assert(0);
 	}
+	return {};
 }
 
 // This function define the needed parameters for each filter.