diff --git a/src/Chart.vala b/src/Chart.vala
index 2cbb2e5..6c3ff4d 100644
--- a/src/Chart.vala
+++ b/src/Chart.vala
@@ -271,43 +271,6 @@ namespace CairoChart {
 			}
 		}
 
-		protected virtual void join_relative_y_axes (Series s,
-		                                             int si,
-		                                             bool calc_max_values,
-		                                             ref double max_rec_width,
-		                                             ref double max_rec_height,
-		                                             ref double max_font_indent,
-		                                             ref double max_axis_font_width,
-		                                             ref int nskip) {
-			for (int sj = si - 1; sj >= 0; --sj) {
-				var s2 = series[sj];
-				if (!s2.zoom_show) continue;
-				bool has_intersection = false;
-				for (int sk = si; sk > sj; --sk) {
-					var s3 = series[sk];
-					if (!s3.zoom_show) continue;
-					if (math.are_intersect(s2.place.zoom_y_min, s2.place.zoom_y_max, s3.place.zoom_y_min, s3.place.zoom_y_max)
-					    || s2.axis_y.position != s3.axis_y.position
-					    || s2.axis_y.type != s3.axis_y.type) {
-						has_intersection = true;
-						break;
-					}
-				}
-				if (!has_intersection) {
-					double tmp_max_rec_width = 0; double tmp_max_rec_height = 0;
-					s2.axis_y.calc_rec_sizes (this, out tmp_max_rec_width, out tmp_max_rec_height, false);
-					max_rec_width = double.max (max_rec_width, tmp_max_rec_width);
-					max_rec_height = double.max (max_rec_height, tmp_max_rec_height);
-					max_font_indent = double.max (max_font_indent, s2.axis_y.font_indent);
-					max_axis_font_width = double.max (max_axis_font_width, s2.axis_y.title.text == "" ? 0
-					                                   : s2.axis_y.title.get_width(context) + s.axis_y.font_indent);
-					++nskip;
-				} else {
-					break;
-				}
-			}
-		}
-
 		protected virtual void calc_plot_area () {
 			plot_x_min = cur_x_min + legend.indent;
 			plot_x_max = cur_x_max - legend.indent;
@@ -363,7 +326,7 @@ namespace CairoChart {
 				var max_font_indent = s.axis_y.font_indent;
 				var max_axis_font_width = s.axis_y.title.text == "" ? 0 : s.axis_y.title.get_width(context) + s.axis_y.font_indent;
 
-				join_relative_y_axes (s, si, true, ref max_rec_width, ref max_rec_height, ref max_font_indent, ref max_axis_font_width, ref nskip);
+				s.join_relative_y_axes (this, si, true, ref max_rec_width, ref max_rec_height, ref max_font_indent, ref max_axis_font_width, ref nskip);
 
 				// for 4.2. Cursor values for joint Y axis
 				if (joint_y && si == zoom_first_show && cursor_style.orientation == Cursor.Orientation.HORIZONTAL && cursors_crossings.length != 0) {
@@ -645,7 +608,7 @@ namespace CairoChart {
 				context.stroke ();
 
 				double tmp1 = 0, tmp2 = 0, tmp3 = 0, tmp4 = 0;
-				join_relative_y_axes (s, si, false, ref tmp1, ref tmp2, ref tmp3, ref tmp4, ref nskip);
+				s.join_relative_y_axes (this, si, false, ref tmp1, ref tmp2, ref tmp3, ref tmp4, ref nskip);
 
 				if (nskip != 0) {--nskip; continue;}
 
diff --git a/src/Series.vala b/src/Series.vala
index 1060e30..267e35a 100644
--- a/src/Series.vala
+++ b/src/Series.vala
@@ -109,5 +109,44 @@ namespace CairoChart {
 				return false;
 			return true;
 		}
+
+		public virtual void join_relative_y_axes (Chart chart,
+		                                             int si,
+		                                             bool calc_max_values,
+		                                             ref double max_rec_width,
+		                                             ref double max_rec_height,
+		                                             ref double max_font_indent,
+		                                             ref double max_axis_font_width,
+		                                             ref int nskip) {
+			for (int sj = si - 1; sj >= 0; --sj) {
+				var s2 = chart.series[sj];
+				if (!s2.zoom_show) continue;
+				bool has_intersection = false;
+				for (int sk = si; sk > sj; --sk) {
+					var s3 = chart.series[sk];
+					if (!s3.zoom_show) continue;
+					if (chart.math.are_intersect(s2.place.zoom_y_min, s2.place.zoom_y_max, s3.place.zoom_y_min, s3.place.zoom_y_max)
+					    || s2.axis_y.position != s3.axis_y.position
+					    || s2.axis_y.type != s3.axis_y.type) {
+						has_intersection = true;
+						break;
+					}
+				}
+				if (!has_intersection) {
+					double tmp_max_rec_width = 0; double tmp_max_rec_height = 0;
+					s2.axis_y.calc_rec_sizes (chart, out tmp_max_rec_width, out tmp_max_rec_height, false);
+					max_rec_width = double.max (max_rec_width, tmp_max_rec_width);
+					max_rec_height = double.max (max_rec_height, tmp_max_rec_height);
+					max_font_indent = double.max (max_font_indent, s2.axis_y.font_indent);
+					max_axis_font_width = double.max (max_axis_font_width, s2.axis_y.title.text == "" ? 0
+					                                   : s2.axis_y.title.get_width(chart.context) + this.axis_y.font_indent);
+					++nskip;
+				} else {
+					break;
+				}
+			}
+		}
+
+
 	}
 }