diff --git a/types/c3/index.d.ts b/types/c3/index.d.ts
index 287e030445..afae3cff31 100644
--- a/types/c3/index.d.ts
+++ b/types/c3/index.d.ts
@@ -459,11 +459,11 @@ declare namespace c3 {
         /**
          * Set max value of x axis range.
          */
-        max?: number;
+        max?: string | number | Date;
         /**
          * Set min value of x axis range.
          */
-        min?: number;
+        min?: string | number | Date;
         /**
          * Set padding for x axis.
          * If this option is set, the range of x axis will increase/decrease according to the values. If no padding is needed in the ragen of x axis, 0 should be set. On category axis, this option