diff --git a/chartist/chartist-tests.ts b/chartist/chartist-tests.ts
index f4ec32f2a..22b10e8b0 100644
--- a/chartist/chartist-tests.ts
+++ b/chartist/chartist-tests.ts
@@ -242,6 +242,26 @@ new Chartist.Line('.ct-chart', {
     }
   });
 
+new Chartist.Line('.ct-chart', {
+  labels: [1, 2, 3, 4, 5, 6, 7, 8],
+  series: [
+    [5, 9, 7, 8, 5, 3, 5, 4]
+  ]
+}, {
+    ticks: [0, 4],
+    low: 0,
+    showArea: true,
+    axisX: {
+      showGrid: false
+    },
+    axisY: {
+      showLabel: true,
+      showGrid: false,
+      ticks: [1, 4],
+      type: Chartist.FixedScaleAxis
+    }
+  });
+
 var chart2 = new Chartist.Line('.ct-chart', {
   labels: [1, 2, 3, 4, 5],
   series: [
diff --git a/chartist/chartist.d.ts b/chartist/chartist.d.ts
index 8d63696f6..a38aa4ce7 100644
--- a/chartist/chartist.d.ts
+++ b/chartist/chartist.d.ts
@@ -305,13 +305,13 @@ declare module Chartist {
   }
 
   interface IChartistStepAxis extends ILineChartAxis {
-    type: IStepAxisStatic;
+    type?: IStepAxisStatic;
     ticks?: Array<string> | Array<number>;
     stretch?: boolean;
   }
 
   interface IChartistFixedScaleAxis extends ILineChartAxis {
-    type: IFixedScaleAxisStatic;
+    type?: IFixedScaleAxisStatic;
     high?: number;
     low?: number;
     divisor?: number;
@@ -324,7 +324,7 @@ declare module Chartist {
     scaleMinSpace?: number;
     onlyInteger?: boolean;
     referenceValue?: number;
-    type: IAutoScaleAxisStatic;
+    type?: IAutoScaleAxisStatic;
   }
 
   interface ILineChartClasses {