diff --git a/src/components/info/info.js b/src/components/info/info.js
index 9703fef22..4eb69b49f 100644
--- a/src/components/info/info.js
+++ b/src/components/info/info.js
@@ -20,9 +20,13 @@ const pluralise = (word, n) => {
 };
 
 const styliseDateRange = (dateStr) => {
-  // 2012-01-22
   const fields = dateStr.split('-');
-  return `${months[fields[1]]} ${fields[0]}`;
+  // 2012-01-22
+  if (fields.length==3){
+    return `${months[fields[1]]} ${fields[0]}`;
+  }else{ // other cases like negative numbers
+    return dateStr;
+  }
 };
 
 const getNumSelectedTips = (nodes, visibility) => {
diff --git a/src/util/dateHelpers.js b/src/util/dateHelpers.js
index 5668cb0b6..0972b9ea3 100644
--- a/src/util/dateHelpers.js
+++ b/src/util/dateHelpers.js
@@ -8,6 +8,9 @@ const dateScale = scaleTime()
   .range([2000, 2100]);
 
 export const numericToCalendar = (numDate) => {
+  if (numDate<0){
+    return Math.round(numDate).toString();
+  }
   const d3Date = dateScale.invert(numDate);
   const calDate = dateFormatter(d3Date);
   return calDate;