diff --git a/superset/assets/src/explore/store.js b/superset/assets/src/explore/store.js
index 4f1e7b5612c1c..f94585b29cf02 100644
--- a/superset/assets/src/explore/store.js
+++ b/superset/assets/src/explore/store.js
@@ -56,6 +56,10 @@ export function getControlsState(state, form_data) {
       delete control.mapStateToProps;
     }
 
+    if (control.multi && typeof formData[k] === 'string') {
+        formData[k] = [formData[k]];
+    }
+
     // If the value is not valid anymore based on choices, clear it
     if (control.type === 'SelectControl' && control.choices && k !== 'datasource' && formData[k]) {
       const choiceValues = control.choices.map(c => c[0]);