diff --git a/src/deepmerge-into.ts b/src/deepmerge-into.ts
index 78b5eb77..c63d495e 100644
--- a/src/deepmerge-into.ts
+++ b/src/deepmerge-into.ts
@@ -140,7 +140,10 @@ export function deepmergeIntoCustom<
  *
  * @param options - The options the user specified
  */
-function getIntoUtils<M, MM extends DeepMergeBuiltInMetaData>(
+function getIntoUtils<
+  M,
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
+>(
   options: DeepMergeIntoOptions<M, MM>,
   customizedDeepmergeInto: DeepMergeMergeIntoFunctionUtils<
     M,
@@ -183,7 +186,7 @@ export function mergeUnknownsInto<
   Ts extends ReadonlyArray<unknown>,
   U extends DeepMergeMergeIntoFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   m_target: Reference<unknown>,
   values: Ts,
@@ -262,7 +265,7 @@ export function mergeUnknownsInto<
 function mergeRecordsInto<
   U extends DeepMergeMergeIntoFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   m_target: Reference<Record<PropertyKey, unknown>>,
   values: ReadonlyArray<Readonly<Record<PropertyKey, unknown>>>,
@@ -295,7 +298,7 @@ function mergeRecordsInto<
 function mergeArraysInto<
   U extends DeepMergeMergeIntoFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   m_target: Reference<unknown[]>,
   values: ReadonlyArray<ReadonlyArray<unknown>>,
@@ -323,7 +326,7 @@ function mergeArraysInto<
 function mergeSetsInto<
   U extends DeepMergeMergeIntoFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   m_target: Reference<Set<unknown>>,
   values: ReadonlyArray<Readonly<ReadonlySet<unknown>>>,
@@ -346,7 +349,7 @@ function mergeSetsInto<
 function mergeMapsInto<
   U extends DeepMergeMergeIntoFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   m_target: Reference<Map<unknown, unknown>>,
   values: ReadonlyArray<Readonly<ReadonlyMap<unknown, unknown>>>,
@@ -369,7 +372,7 @@ function mergeMapsInto<
 function mergeOthersInto<
   U extends DeepMergeMergeIntoFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   m_target: Reference<unknown>,
   values: ReadonlyArray<unknown>,
diff --git a/src/deepmerge.ts b/src/deepmerge.ts
index 8007a01f..13b737a0 100644
--- a/src/deepmerge.ts
+++ b/src/deepmerge.ts
@@ -108,7 +108,10 @@ export function deepmergeCustom<
  *
  * @param options - The options the user specified
  */
-function getUtils<M, MM extends DeepMergeBuiltInMetaData>(
+function getUtils<
+  M,
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
+>(
   options: DeepMergeOptions<M, MM>,
   customizedDeepmerge: DeepMergeMergeFunctionUtils<M, MM>["deepmerge"]
 ): DeepMergeMergeFunctionUtils<M, MM> {
@@ -147,7 +150,7 @@ export function mergeUnknowns<
   U extends DeepMergeMergeFunctionUtils<M, MM>,
   MF extends DeepMergeMergeFunctionsURIs,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(values: Ts, utils: U, meta: M | undefined): DeepMergeHKT<Ts, MF, M> {
   if (values.length === 0) {
     return undefined as DeepMergeHKT<Ts, MF, M>;
@@ -230,7 +233,7 @@ function mergeRecords<
   U extends DeepMergeMergeFunctionUtils<M, MM>,
   MF extends DeepMergeMergeFunctionsURIs,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   values: ReadonlyArray<Readonly<Record<PropertyKey, unknown>>>,
   utils: U,
@@ -265,7 +268,7 @@ function mergeRecords<
 function mergeArrays<
   U extends DeepMergeMergeFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   values: ReadonlyArray<Readonly<ReadonlyArray<unknown>>>,
   utils: U,
@@ -293,7 +296,7 @@ function mergeArrays<
 function mergeSets<
   U extends DeepMergeMergeFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   values: ReadonlyArray<Readonly<ReadonlySet<unknown>>>,
   utils: U,
@@ -320,7 +323,7 @@ function mergeSets<
 function mergeMaps<
   U extends DeepMergeMergeFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   values: ReadonlyArray<Readonly<ReadonlyMap<unknown, unknown>>>,
   utils: U,
@@ -347,7 +350,7 @@ function mergeMaps<
 function mergeOthers<
   U extends DeepMergeMergeFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(values: ReadonlyArray<unknown>, utils: U, meta: M | undefined) {
   const result = utils.mergeFunctions.mergeOthers(values, utils, meta);
 
diff --git a/src/defaults/into.ts b/src/defaults/into.ts
index 8bd5b3f7..256e173d 100644
--- a/src/defaults/into.ts
+++ b/src/defaults/into.ts
@@ -31,7 +31,7 @@ export function mergeRecords<
   Ts extends ReadonlyArray<Record<PropertyKey, unknown>>,
   U extends DeepMergeMergeIntoFunctionUtils<M, MM>,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   m_target: Reference<Record<PropertyKey, unknown>>,
   values: Ts,
diff --git a/src/defaults/vanilla.ts b/src/defaults/vanilla.ts
index 9883f786..c4e10597 100644
--- a/src/defaults/vanilla.ts
+++ b/src/defaults/vanilla.ts
@@ -36,7 +36,7 @@ export function mergeRecords<
   U extends DeepMergeMergeFunctionUtils<M, MM>,
   MF extends DeepMergeMergeFunctionsURIs,
   M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 >(
   values: Ts,
   utils: U,
diff --git a/src/types/options.ts b/src/types/options.ts
index d6c5bc82..5266021f 100644
--- a/src/types/options.ts
+++ b/src/types/options.ts
@@ -8,7 +8,7 @@ import type { DeepMergeBuiltInMetaData } from "./merging.js";
  */
 export type DeepMergeOptions<
   in out M,
-  MM extends Readonly<Record<PropertyKey, unknown>> = DeepMergeBuiltInMetaData
+  MM extends Readonly<Record<PropertyKey, unknown>> = {}
 > = Partial<DeepMergeOptionsFull<M, MM & DeepMergeBuiltInMetaData>>;
 
 /**
@@ -16,20 +16,20 @@ export type DeepMergeOptions<
  */
 export type DeepMergeIntoOptions<
   in out M,
-  MM extends Readonly<Record<PropertyKey, unknown>> = DeepMergeBuiltInMetaData
+  MM extends Readonly<Record<PropertyKey, unknown>> = {}
 > = Partial<DeepMergeIntoOptionsFull<M, MM & DeepMergeBuiltInMetaData>>;
 
-type MetaDataUpdater<in out M, MM extends DeepMergeBuiltInMetaData> = (
-  previousMeta: M | undefined,
-  metaMeta: Readonly<Partial<MM>>
-) => M;
+type MetaDataUpdater<
+  in out M,
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
+> = (previousMeta: M | undefined, metaMeta: Readonly<Partial<MM>>) => M;
 
 /**
  * All the options the user can pass to customize deepmerge.
  */
 type DeepMergeOptionsFull<
   in out M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 > = Readonly<{
   mergeRecords: DeepMergeMergeFunctions<M, MM>["mergeRecords"] | false;
   mergeArrays: DeepMergeMergeFunctions<M, MM>["mergeArrays"] | false;
@@ -45,7 +45,7 @@ type DeepMergeOptionsFull<
  */
 type DeepMergeIntoOptionsFull<
   in out M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 > = Readonly<{
   mergeRecords: DeepMergeMergeIntoFunctions<M, MM>["mergeRecords"] | false;
   mergeArrays: DeepMergeMergeIntoFunctions<M, MM>["mergeArrays"] | false;
@@ -67,7 +67,7 @@ export type Reference<T> = {
  */
 type DeepMergeMergeFunctions<
   in M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 > = Readonly<{
   mergeRecords: <
     Ts extends ReadonlyArray<Readonly<Record<PropertyKey, unknown>>>,
@@ -123,7 +123,7 @@ type DeepMergeMergeIntoFunctionsReturnType = void | symbol;
  */
 type DeepMergeMergeIntoFunctions<
   in M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 > = Readonly<{
   mergeRecords: <
     Ts extends ReadonlyArray<Readonly<Record<PropertyKey, unknown>>>,
@@ -182,7 +182,7 @@ type DeepMergeMergeIntoFunctions<
 // eslint-disable-next-line functional/no-mixed-types
 export type DeepMergeMergeFunctionUtils<
   in out M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 > = Readonly<{
   mergeFunctions: DeepMergeMergeFunctions<M, MM>;
   defaultMergeFunctions: MergeFunctions;
@@ -201,7 +201,7 @@ export type DeepMergeMergeFunctionUtils<
 // eslint-disable-next-line functional/no-mixed-types
 export type DeepMergeMergeIntoFunctionUtils<
   in out M,
-  MM extends DeepMergeBuiltInMetaData
+  MM extends DeepMergeBuiltInMetaData = DeepMergeBuiltInMetaData
 > = Readonly<{
   mergeFunctions: DeepMergeMergeIntoFunctions<M, MM>;
   defaultMergeFunctions: MergeIntoFunctions;