diff --git a/src/plugins/data/public/search/aggs/metrics/bucket_avg_fn.ts b/src/plugins/data/public/search/aggs/metrics/bucket_avg_fn.ts
index f4f7dd5f93600..56643a2df54bd 100644
--- a/src/plugins/data/public/search/aggs/metrics/bucket_avg_fn.ts
+++ b/src/plugins/data/public/search/aggs/metrics/bucket_avg_fn.ts
@@ -88,11 +88,6 @@ export const aggBucketAvg = (): FunctionDefinition => ({
   fn: (input, args) => {
     const { id, enabled, schema, ...rest } = args;
 
-    // Need to spread this object to work around TS bug:
-    // https://github.com/microsoft/TypeScript/issues/15300#issuecomment-436793742
-    const customBucket = args.customBucket?.value ? { ...args.customBucket.value } : undefined;
-    const customMetric = args.customMetric?.value ? { ...args.customMetric.value } : undefined;
-
     return {
       type: 'agg_type',
       value: {
@@ -102,8 +97,8 @@ export const aggBucketAvg = (): FunctionDefinition => ({
         type: METRIC_TYPES.AVG_BUCKET,
         params: {
           ...rest,
-          customBucket,
-          customMetric,
+          customBucket: args.customBucket?.value,
+          customMetric: args.customMetric?.value,
           json: getParsedValue(args, 'json'),
         },
       },
diff --git a/src/plugins/data/public/search/aggs/metrics/bucket_max_fn.ts b/src/plugins/data/public/search/aggs/metrics/bucket_max_fn.ts
index 5d8c22b7886cd..896e9cf839605 100644
--- a/src/plugins/data/public/search/aggs/metrics/bucket_max_fn.ts
+++ b/src/plugins/data/public/search/aggs/metrics/bucket_max_fn.ts
@@ -88,11 +88,6 @@ export const aggBucketMax = (): FunctionDefinition => ({
   fn: (input, args) => {
     const { id, enabled, schema, ...rest } = args;
 
-    // Need to spread this object to work around TS bug:
-    // https://github.com/microsoft/TypeScript/issues/15300#issuecomment-436793742
-    const customBucket = args.customBucket?.value ? { ...args.customBucket.value } : undefined;
-    const customMetric = args.customMetric?.value ? { ...args.customMetric.value } : undefined;
-
     return {
       type: 'agg_type',
       value: {
@@ -102,8 +97,8 @@ export const aggBucketMax = (): FunctionDefinition => ({
         type: METRIC_TYPES.MAX_BUCKET,
         params: {
           ...rest,
-          customBucket,
-          customMetric,
+          customBucket: args.customBucket?.value,
+          customMetric: args.customMetric?.value,
           json: getParsedValue(args, 'json'),
         },
       },
diff --git a/src/plugins/data/public/search/aggs/metrics/bucket_min_fn.ts b/src/plugins/data/public/search/aggs/metrics/bucket_min_fn.ts
index b9914fd0439e4..2ae3d9211227a 100644
--- a/src/plugins/data/public/search/aggs/metrics/bucket_min_fn.ts
+++ b/src/plugins/data/public/search/aggs/metrics/bucket_min_fn.ts
@@ -88,11 +88,6 @@ export const aggBucketMin = (): FunctionDefinition => ({
   fn: (input, args) => {
     const { id, enabled, schema, ...rest } = args;
 
-    // Need to spread this object to work around TS bug:
-    // https://github.com/microsoft/TypeScript/issues/15300#issuecomment-436793742
-    const customBucket = args.customBucket?.value ? { ...args.customBucket.value } : undefined;
-    const customMetric = args.customMetric?.value ? { ...args.customMetric.value } : undefined;
-
     return {
       type: 'agg_type',
       value: {
@@ -102,8 +97,8 @@ export const aggBucketMin = (): FunctionDefinition => ({
         type: METRIC_TYPES.MIN_BUCKET,
         params: {
           ...rest,
-          customBucket,
-          customMetric,
+          customBucket: args.customBucket?.value,
+          customMetric: args.customMetric?.value,
           json: getParsedValue(args, 'json'),
         },
       },
diff --git a/src/plugins/data/public/search/aggs/metrics/bucket_sum_fn.ts b/src/plugins/data/public/search/aggs/metrics/bucket_sum_fn.ts
index 35a599a402fe1..eceb11a90f293 100644
--- a/src/plugins/data/public/search/aggs/metrics/bucket_sum_fn.ts
+++ b/src/plugins/data/public/search/aggs/metrics/bucket_sum_fn.ts
@@ -88,11 +88,6 @@ export const aggBucketSum = (): FunctionDefinition => ({
   fn: (input, args) => {
     const { id, enabled, schema, ...rest } = args;
 
-    // Need to spread this object to work around TS bug:
-    // https://github.com/microsoft/TypeScript/issues/15300#issuecomment-436793742
-    const customBucket = args.customBucket?.value ? { ...args.customBucket.value } : undefined;
-    const customMetric = args.customMetric?.value ? { ...args.customMetric.value } : undefined;
-
     return {
       type: 'agg_type',
       value: {
@@ -102,8 +97,8 @@ export const aggBucketSum = (): FunctionDefinition => ({
         type: METRIC_TYPES.SUM_BUCKET,
         params: {
           ...rest,
-          customBucket,
-          customMetric,
+          customBucket: args.customBucket?.value,
+          customMetric: args.customMetric?.value,
           json: getParsedValue(args, 'json'),
         },
       },
diff --git a/src/plugins/data/public/search/aggs/metrics/cumulative_sum_fn.ts b/src/plugins/data/public/search/aggs/metrics/cumulative_sum_fn.ts
index 65c9958c8ebd2..1c2ed87ba2055 100644
--- a/src/plugins/data/public/search/aggs/metrics/cumulative_sum_fn.ts
+++ b/src/plugins/data/public/search/aggs/metrics/cumulative_sum_fn.ts
@@ -93,10 +93,6 @@ export const aggCumulativeSum = (): FunctionDefinition => ({
   fn: (input, args) => {
     const { id, enabled, schema, ...rest } = args;
 
-    // Need to spread this object to work around TS bug:
-    // https://github.com/microsoft/TypeScript/issues/15300#issuecomment-436793742
-    const customMetric = args.customMetric?.value ? { ...args.customMetric.value } : undefined;
-
     return {
       type: 'agg_type',
       value: {
@@ -106,7 +102,7 @@ export const aggCumulativeSum = (): FunctionDefinition => ({
         type: METRIC_TYPES.CUMULATIVE_SUM,
         params: {
           ...rest,
-          customMetric,
+          customMetric: args.customMetric?.value,
           json: getParsedValue(args, 'json'),
         },
       },
diff --git a/src/plugins/data/public/search/aggs/metrics/derivative_fn.ts b/src/plugins/data/public/search/aggs/metrics/derivative_fn.ts
index b6557d5f99219..e97a7813b2ca6 100644
--- a/src/plugins/data/public/search/aggs/metrics/derivative_fn.ts
+++ b/src/plugins/data/public/search/aggs/metrics/derivative_fn.ts
@@ -93,10 +93,6 @@ export const aggDerivative = (): FunctionDefinition => ({
   fn: (input, args) => {
     const { id, enabled, schema, ...rest } = args;
 
-    // Need to spread this object to work around TS bug:
-    // https://github.com/microsoft/TypeScript/issues/15300#issuecomment-436793742
-    const customMetric = args.customMetric?.value ? { ...args.customMetric.value } : undefined;
-
     return {
       type: 'agg_type',
       value: {
@@ -106,7 +102,7 @@ export const aggDerivative = (): FunctionDefinition => ({
         type: METRIC_TYPES.DERIVATIVE,
         params: {
           ...rest,
-          customMetric,
+          customMetric: args.customMetric?.value,
           json: getParsedValue(args, 'json'),
         },
       },
diff --git a/src/plugins/data/public/search/aggs/metrics/moving_avg_fn.ts b/src/plugins/data/public/search/aggs/metrics/moving_avg_fn.ts
index bd0806eb4effb..662853d5412ff 100644
--- a/src/plugins/data/public/search/aggs/metrics/moving_avg_fn.ts
+++ b/src/plugins/data/public/search/aggs/metrics/moving_avg_fn.ts
@@ -106,10 +106,6 @@ export const aggMovingAvg = (): FunctionDefinition => ({
   fn: (input, args) => {
     const { id, enabled, schema, ...rest } = args;
 
-    // Need to spread this object to work around TS bug:
-    // https://github.com/microsoft/TypeScript/issues/15300#issuecomment-436793742
-    const customMetric = args.customMetric?.value ? { ...args.customMetric.value } : undefined;
-
     return {
       type: 'agg_type',
       value: {
@@ -119,7 +115,7 @@ export const aggMovingAvg = (): FunctionDefinition => ({
         type: METRIC_TYPES.MOVING_FN,
         params: {
           ...rest,
-          customMetric,
+          customMetric: args.customMetric?.value,
           json: getParsedValue(args, 'json'),
         },
       },
diff --git a/src/plugins/data/public/search/aggs/metrics/serial_diff_fn.ts b/src/plugins/data/public/search/aggs/metrics/serial_diff_fn.ts
index f9635c092947a..6d991624f1652 100644
--- a/src/plugins/data/public/search/aggs/metrics/serial_diff_fn.ts
+++ b/src/plugins/data/public/search/aggs/metrics/serial_diff_fn.ts
@@ -93,10 +93,6 @@ export const aggSerialDiff = (): FunctionDefinition => ({
   fn: (input, args) => {
     const { id, enabled, schema, ...rest } = args;
 
-    // Need to spread this object to work around TS bug:
-    // https://github.com/microsoft/TypeScript/issues/15300#issuecomment-436793742
-    const customMetric = args.customMetric?.value ? { ...args.customMetric.value } : undefined;
-
     return {
       type: 'agg_type',
       value: {
@@ -106,7 +102,7 @@ export const aggSerialDiff = (): FunctionDefinition => ({
         type: METRIC_TYPES.SERIAL_DIFF,
         params: {
           ...rest,
-          customMetric,
+          customMetric: args.customMetric?.value,
           json: getParsedValue(args, 'json'),
         },
       },