diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3d6eb9ad..10a3da93 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,13 @@
 # Changelog
 All notable changes to this project will be documented in this file. Dates are displayed in UTC.
 
+## [4.0.4](https://github.com/RebeccaStevens/deepmerge-ts/compare/v4.0.3...v4.0.4) (2022-06-13)
+
+
+### Bug Fixes
+
+* drop keys that have no enumerable properties ([3363570](https://github.com/RebeccaStevens/deepmerge-ts/commit/3363570fcc53488d22a2d4b778b558173c7ee5c9))
+
 ## [4.0.3](https://github.com/RebeccaStevens/deepmerge-ts/compare/v4.0.2...v4.0.3) (2022-04-06)
 
 
diff --git a/dist/deno/deepmerge.ts b/dist/deno/deepmerge.ts
index 87559716..7ce13713 100644
--- a/dist/deno/deepmerge.ts
+++ b/dist/deno/deepmerge.ts
@@ -203,8 +203,8 @@ function mergeUnknowns<
   // eslint-disable-next-line functional/no-conditional-statement -- add an early escape for better performance.
   if (type !== ObjectType.NOT && type !== ObjectType.OTHER) {
     // eslint-disable-next-line functional/no-loop-statement -- using a loop here is more performant than mapping every value and then testing every value.
-    for (let mutableIndex = 1; mutableIndex < values.length; mutableIndex++) {
-      if (getObjectType(values[mutableIndex]) === type) {
+    for (let m_index = 1; m_index < values.length; m_index++) {
+      if (getObjectType(values[m_index]) === type) {
         continue;
       }
 
@@ -425,7 +425,9 @@ function defaultMergeRecords<
       }
     }
 
-    // assert(propValues.length > 0);
+    if (propValues.length === 0) {
+      continue;
+    }
 
     const updatedMeta = utils.metaDataUpdater(meta, {
       key,
diff --git a/dist/deno/types/options.ts b/dist/deno/types/options.ts
index d05f5457..890d3d63 100644
--- a/dist/deno/types/options.ts
+++ b/dist/deno/types/options.ts
@@ -1,4 +1,4 @@
-// eslint-disable-next-line import/no-relative-parent-imports -- use "@/deepmerge" once denoify can support it.
+// eslint-disable-next-line import/no-relative-parent-imports -- use "deepmerge-ts" once denoify can support it.
 import type { DeepMergeMergeFunctionsDefaults } from "../index.ts";
 
 import type { DeepMergeBuiltInMetaData } from "./merging.ts";
diff --git a/dist/node/index.cjs b/dist/node/index.cjs
index 293768e1..4f2ef872 100644
--- a/dist/node/index.cjs
+++ b/dist/node/index.cjs
@@ -12,21 +12,21 @@ var isPlainObject = require('is-plain-object');
  */
 function getObjectType(object) {
     if (typeof object !== "object" || object === null) {
-        return 0 /* NOT */;
+        return 0 /* ObjectType.NOT */;
     }
     if (Array.isArray(object)) {
-        return 2 /* ARRAY */;
+        return 2 /* ObjectType.ARRAY */;
     }
     if (isPlainObject.isPlainObject(object)) {
-        return 1 /* RECORD */;
+        return 1 /* ObjectType.RECORD */;
     }
     if (object instanceof Set) {
-        return 3 /* SET */;
+        return 3 /* ObjectType.SET */;
     }
     if (object instanceof Map) {
-        return 4 /* MAP */;
+        return 4 /* ObjectType.MAP */;
     }
-    return 5 /* OTHER */;
+    return 5 /* ObjectType.OTHER */;
 }
 /**
  * Get the keys of the given objects including symbol keys.
@@ -151,23 +151,23 @@ function mergeUnknowns(values, utils, meta) {
     }
     const type = getObjectType(values[0]);
     // eslint-disable-next-line functional/no-conditional-statement -- add an early escape for better performance.
-    if (type !== 0 /* NOT */ && type !== 5 /* OTHER */) {
+    if (type !== 0 /* ObjectType.NOT */ && type !== 5 /* ObjectType.OTHER */) {
         // eslint-disable-next-line functional/no-loop-statement -- using a loop here is more performant than mapping every value and then testing every value.
-        for (let mutableIndex = 1; mutableIndex < values.length; mutableIndex++) {
-            if (getObjectType(values[mutableIndex]) === type) {
+        for (let m_index = 1; m_index < values.length; m_index++) {
+            if (getObjectType(values[m_index]) === type) {
                 continue;
             }
             return mergeOthers(values, utils, meta);
         }
     }
     switch (type) {
-        case 1 /* RECORD */:
+        case 1 /* ObjectType.RECORD */:
             return mergeRecords(values, utils, meta);
-        case 2 /* ARRAY */:
+        case 2 /* ObjectType.ARRAY */:
             return mergeArrays(values, utils, meta);
-        case 3 /* SET */:
+        case 3 /* ObjectType.SET */:
             return mergeSets(values, utils, meta);
-        case 4 /* MAP */:
+        case 4 /* ObjectType.MAP */:
             return mergeMaps(values, utils, meta);
         default:
             return mergeOthers(values, utils, meta);
@@ -266,7 +266,9 @@ function defaultMergeRecords(values, utils, meta) {
                 propValues.push(value[key]);
             }
         }
-        // assert(propValues.length > 0);
+        if (propValues.length === 0) {
+            continue;
+        }
         const updatedMeta = utils.metaDataUpdater(meta, {
             key,
             parents: values,
diff --git a/dist/node/index.mjs b/dist/node/index.mjs
index 3ed233d6..45e22ff9 100644
--- a/dist/node/index.mjs
+++ b/dist/node/index.mjs
@@ -8,21 +8,21 @@ import { isPlainObject } from 'is-plain-object';
  */
 function getObjectType(object) {
     if (typeof object !== "object" || object === null) {
-        return 0 /* NOT */;
+        return 0 /* ObjectType.NOT */;
     }
     if (Array.isArray(object)) {
-        return 2 /* ARRAY */;
+        return 2 /* ObjectType.ARRAY */;
     }
     if (isPlainObject(object)) {
-        return 1 /* RECORD */;
+        return 1 /* ObjectType.RECORD */;
     }
     if (object instanceof Set) {
-        return 3 /* SET */;
+        return 3 /* ObjectType.SET */;
     }
     if (object instanceof Map) {
-        return 4 /* MAP */;
+        return 4 /* ObjectType.MAP */;
     }
-    return 5 /* OTHER */;
+    return 5 /* ObjectType.OTHER */;
 }
 /**
  * Get the keys of the given objects including symbol keys.
@@ -147,23 +147,23 @@ function mergeUnknowns(values, utils, meta) {
     }
     const type = getObjectType(values[0]);
     // eslint-disable-next-line functional/no-conditional-statement -- add an early escape for better performance.
-    if (type !== 0 /* NOT */ && type !== 5 /* OTHER */) {
+    if (type !== 0 /* ObjectType.NOT */ && type !== 5 /* ObjectType.OTHER */) {
         // eslint-disable-next-line functional/no-loop-statement -- using a loop here is more performant than mapping every value and then testing every value.
-        for (let mutableIndex = 1; mutableIndex < values.length; mutableIndex++) {
-            if (getObjectType(values[mutableIndex]) === type) {
+        for (let m_index = 1; m_index < values.length; m_index++) {
+            if (getObjectType(values[m_index]) === type) {
                 continue;
             }
             return mergeOthers(values, utils, meta);
         }
     }
     switch (type) {
-        case 1 /* RECORD */:
+        case 1 /* ObjectType.RECORD */:
             return mergeRecords(values, utils, meta);
-        case 2 /* ARRAY */:
+        case 2 /* ObjectType.ARRAY */:
             return mergeArrays(values, utils, meta);
-        case 3 /* SET */:
+        case 3 /* ObjectType.SET */:
             return mergeSets(values, utils, meta);
-        case 4 /* MAP */:
+        case 4 /* ObjectType.MAP */:
             return mergeMaps(values, utils, meta);
         default:
             return mergeOthers(values, utils, meta);
@@ -262,7 +262,9 @@ function defaultMergeRecords(values, utils, meta) {
                 propValues.push(value[key]);
             }
         }
-        // assert(propValues.length > 0);
+        if (propValues.length === 0) {
+            continue;
+        }
         const updatedMeta = utils.metaDataUpdater(meta, {
             key,
             parents: values,