diff --git a/src/traces/bar/set_positions.js b/src/traces/bar/set_positions.js
index 14daefccfe4..6b80bec85c9 100644
--- a/src/traces/bar/set_positions.js
+++ b/src/traces/bar/set_positions.js
@@ -144,7 +144,7 @@ module.exports = function setPositions(gd, plotinfo) {
                 for(j = 0; j < ti.length; j++) {
                     sv = Math.round(ti[j].p / sumround);
                     // store the negative sum value for p at the same key, with sign flipped
-                    if(relative && ti[j].s < 0) sv = -sv;
+                    if(relative && ti[j].s < 0) sv = '-' + sv;  // use string to ensure -0 !== 0
                     var previousSum = sums[sv] || 0;
                     if(stack || relative) ti[j].b = previousSum;
                     barEnd = ti[j].b + ti[j].s;
@@ -173,7 +173,7 @@ module.exports = function setPositions(gd, plotinfo) {
                     for(j = 0; j < ti.length; j++) {
                         relAndNegative = relative && ti[j].s < 0;
                         sv = Math.round(ti[j].p / sumround);
-                        if(relAndNegative) sv = -sv;  // locate negative sum amount for this p val
+                        if(relAndNegative) sv = '-' + sv;  // locate negative sum amount for this p val
                         scale = top / sums[sv];
                         if(relAndNegative) scale *= -1; // preserve sign if negative
                         ti[j].b *= scale;