diff --git a/superset/assets/src/visualizations/nvd3/LineMulti/LineMulti.jsx b/superset/assets/src/visualizations/nvd3/LineMulti/LineMulti.jsx
index 525a0f0944c7b..42efb7b013d93 100644
--- a/superset/assets/src/visualizations/nvd3/LineMulti/LineMulti.jsx
+++ b/superset/assets/src/visualizations/nvd3/LineMulti/LineMulti.jsx
@@ -9,7 +9,7 @@ const propTypes = {
   width: PropTypes.number,
   height: PropTypes.number,
   annotationData: PropTypes.object,
-  datasource: PropTypes.array,
+  datasource: PropTypes.object,
   formData: PropTypes.object,
   onAddFilter: PropTypes.func,
   onError: PropTypes.func,
diff --git a/superset/assets/src/visualizations/nvd3/utils.js b/superset/assets/src/visualizations/nvd3/utils.js
index 80ed849e3dc38..bc6873a9d06e2 100644
--- a/superset/assets/src/visualizations/nvd3/utils.js
+++ b/superset/assets/src/visualizations/nvd3/utils.js
@@ -170,7 +170,7 @@ export function getMaxLabelSize(svg, axisClass) {
   const tickTexts = svg.selectAll(`.${axisClass} g.tick text`);
   if (tickTexts.length > 0) {
     const lengths = tickTexts[0].map(text => text.getComputedTextLength());
-    return Math.ceil(Math.max(...lengths));
+    return Math.ceil(Math.max(0, ...lengths));
   }
   return 0;
 }