diff --git a/superset-frontend/src/explore/components/controls/AnnotationLayer.jsx b/superset-frontend/src/explore/components/controls/AnnotationLayer.jsx
index 20fdaecc914..e119e87423f 100644
--- a/superset-frontend/src/explore/components/controls/AnnotationLayer.jsx
+++ b/superset-frontend/src/explore/components/controls/AnnotationLayer.jsx
@@ -240,12 +240,16 @@ export default class AnnotationLayer extends React.PureComponent {
   }
 
   handleAnnotationSourceType(sourceType) {
-    this.setState({
-      sourceType,
-      isLoadingOptions: true,
-      validationErrors: {},
-      value: null,
-    });
+    const { sourceType: prevSourceType } = this.state;
+
+    if (prevSourceType !== sourceType) {
+      this.setState({
+        sourceType,
+        isLoadingOptions: true,
+        validationErrors: {},
+        value: null,
+      });
+    }
   }
 
   handleValue(value) {
diff --git a/superset-frontend/src/explore/components/controls/SelectControl.jsx b/superset-frontend/src/explore/components/controls/SelectControl.jsx
index 968bc076670..b858342a0e3 100644
--- a/superset-frontend/src/explore/components/controls/SelectControl.jsx
+++ b/superset-frontend/src/explore/components/controls/SelectControl.jsx
@@ -96,6 +96,8 @@ export default class SelectControl extends React.PureComponent {
     }
   }
 
+  // Beware: This is acting like an on-click instead of an on-change
+  // (firing every time user chooses vs firing only if a new option is chosen).
   onChange(opt) {
     let optionValue = null;
     if (opt) {