diff --git a/js/highcharts.src.js b/js/highcharts.src.js
index 52027679ff9..a68af5d252a 100644
--- a/js/highcharts.src.js
+++ b/js/highcharts.src.js
@@ -14897,7 +14897,7 @@
             if (seriesOptions.marker) { // line, spline, area, areaspline, scatter
 
                 // if no hover radius is given, default to normal radius + 2
-                stateOptionsHover.radius = stateOptionsHover.radius || normalOptions.radius + stateOptionsHover.radiusPlus;
+                stateOptionsHover.radius = +stateOptionsHover.radius || +normalOptions.radius + +stateOptionsHover.radiusPlus;
                 stateOptionsHover.lineWidth = stateOptionsHover.lineWidth || normalOptions.lineWidth + stateOptionsHover.lineWidthPlus;
 
             } else { // column, bar, pie
diff --git a/js/highmaps.src.js b/js/highmaps.src.js
index 5d6282cccd2..9557916da2c 100644
--- a/js/highmaps.src.js
+++ b/js/highmaps.src.js
@@ -14374,7 +14374,7 @@
             if (seriesOptions.marker) { // line, spline, area, areaspline, scatter
 
                 // if no hover radius is given, default to normal radius + 2
-                stateOptionsHover.radius = stateOptionsHover.radius || normalOptions.radius + stateOptionsHover.radiusPlus;
+                stateOptionsHover.radius = +stateOptionsHover.radius || +normalOptions.radius + +stateOptionsHover.radiusPlus;
                 stateOptionsHover.lineWidth = stateOptionsHover.lineWidth || normalOptions.lineWidth + stateOptionsHover.lineWidthPlus;
 
             } else { // column, bar, pie
diff --git a/js/highstock.src.js b/js/highstock.src.js
index 7f541f61091..b66f558fedb 100644
--- a/js/highstock.src.js
+++ b/js/highstock.src.js
@@ -14897,7 +14897,7 @@
             if (seriesOptions.marker) { // line, spline, area, areaspline, scatter
 
                 // if no hover radius is given, default to normal radius + 2
-                stateOptionsHover.radius = stateOptionsHover.radius || normalOptions.radius + stateOptionsHover.radiusPlus;
+                stateOptionsHover.radius = +stateOptionsHover.radius || +normalOptions.radius + +stateOptionsHover.radiusPlus;
                 stateOptionsHover.lineWidth = stateOptionsHover.lineWidth || normalOptions.lineWidth + stateOptionsHover.lineWidthPlus;
 
             } else { // column, bar, pie
diff --git a/js/parts/Series.js b/js/parts/Series.js
index 2cd487f8dbb..ea7d4b66aa6 100644
--- a/js/parts/Series.js
+++ b/js/parts/Series.js
@@ -1096,7 +1096,7 @@ Series.prototype = {
 		if (seriesOptions.marker) { // line, spline, area, areaspline, scatter
 
 			// if no hover radius is given, default to normal radius + 2
-			stateOptionsHover.radius = stateOptionsHover.radius || normalOptions.radius + stateOptionsHover.radiusPlus;
+			stateOptionsHover.radius = +stateOptionsHover.radius || +normalOptions.radius + +stateOptionsHover.radiusPlus;
 			stateOptionsHover.lineWidth = stateOptionsHover.lineWidth || normalOptions.lineWidth + stateOptionsHover.lineWidthPlus;
 
 		} else { // column, bar, pie