diff --git a/src/plugins/vis_type_timeseries/common/vis_schema.ts b/src/plugins/vis_type_timeseries/common/vis_schema.ts
index d3d863df8617f..b33215934c5df 100644
--- a/src/plugins/vis_type_timeseries/common/vis_schema.ts
+++ b/src/plugins/vis_type_timeseries/common/vis_schema.ts
@@ -111,7 +111,7 @@ export const metricsItems = schema.object({
         field: stringOptionalNullable,
         mode: schema.oneOf([schema.literal('line'), schema.literal('band')]),
         shade: schema.oneOf([numberOptional, stringOptionalNullable]),
-        value: schema.oneOf([numberOptional, stringOptionalNullable]),
+        value: schema.maybe(schema.oneOf([numberOptional, stringOptionalNullable])),
         percentile: stringOptionalNullable,
       })
     )