diff --git a/src/traces/heatmap/calc.js b/src/traces/heatmap/calc.js
index e8611ccc82e..72a0dfb2033 100644
--- a/src/traces/heatmap/calc.js
+++ b/src/traces/heatmap/calc.js
@@ -219,9 +219,9 @@ function makeBoundArray(trace, arrayIn, v0In, dvIn, numbricks, ax) {
     else {
         dv = dvIn || 1;
 
-        if(Array.isArray(arrayIn) && arrayIn.length === 1) v0 = arrayIn[0];
+        if(isHist || ax.type === 'category') v0 = v0In || 0;
+        else if(Array.isArray(arrayIn) && arrayIn.length === 1) v0 = arrayIn[0];
         else if(v0In === undefined) v0 = 0;
-        else if(isHist || ax.type === 'category') v0 = v0In;
         else v0 = ax.d2c(v0In);
 
         for(i = (isContour || isGL2D) ? 0 : -0.5; i < numbricks; i++) {