diff --git a/numass-viewer/src/main/kotlin/inr/numass/viewer/AmplitudeView.kt b/numass-viewer/src/main/kotlin/inr/numass/viewer/AmplitudeView.kt
index ac23e70f..21a3db7e 100644
--- a/numass-viewer/src/main/kotlin/inr/numass/viewer/AmplitudeView.kt
+++ b/numass-viewer/src/main/kotlin/inr/numass/viewer/AmplitudeView.kt
@@ -47,7 +47,7 @@ class AmplitudeView : View(title = "Numass amplitude spectrum plot", icon = Imag
             "showLine" to true
             "showSymbol" to false
             "showErrors" to false
-        }.setType(DataPlot::class)
+        }.setType<DataPlot>()
     }
 
     val binningProperty = SimpleObjectProperty(20)
diff --git a/numass-viewer/src/main/kotlin/inr/numass/viewer/HVView.kt b/numass-viewer/src/main/kotlin/inr/numass/viewer/HVView.kt
index 681395d4..0735e2ac 100644
--- a/numass-viewer/src/main/kotlin/inr/numass/viewer/HVView.kt
+++ b/numass-viewer/src/main/kotlin/inr/numass/viewer/HVView.kt
@@ -34,7 +34,7 @@ class HVView : View(title = "High voltage time plot", icon = ImageView(dfIcon))
             "showSymbol" to false
             "showErrors" to false
         }
-        plots.setType(DataPlot::class)
+        plots.setType<DataPlot>()
     }
     private val container = PlotContainer(frame);
 
@@ -58,7 +58,8 @@ class HVView : View(title = "High voltage time plot", icon = ImageView(dfIcon))
                 } ui { hvData ->
                     hvData?.let {
                         for (dp in it) {
-                            val plot: TimePlot = frame[change.key] as TimePlot? ?: TimePlot(change.key).apply { frame.add(this) }
+                            val plot: TimePlot = frame[change.key] as TimePlot?
+                                    ?: TimePlot(change.key).apply { frame.add(this) }
                             plot.put(dp.getValue("timestamp").time, dp.getValue("value"))
                         }
                     }