diff --git a/src/observable/map/ApplyMap.ts b/src/observable/map/ApplyMap.ts
index 1786873a..ee40c797 100644
--- a/src/observable/map/ApplyMap.ts
+++ b/src/observable/map/ApplyMap.ts
@@ -16,7 +16,7 @@ limitations under the License.
 
 import {BaseObservableMap} from "./BaseObservableMap";
 import {SubscriptionHandle} from "../BaseObservable";
-import {BaseObservableMapDefaults} from "./BaseObservableMapDefaults";
+import {BaseObservableMapTransformers} from "./BaseObservableMapTransformers";
 
 
 export class ApplyMap<K, V> extends BaseObservableMap<K, V> {
@@ -26,7 +26,7 @@ export class ApplyMap<K, V> extends BaseObservableMap<K, V> {
 
 
     constructor(source: BaseObservableMap<K, V>, apply?: Apply<K, V>) {
-        super(new BaseObservableMapDefaults<K, V>());
+        super(new BaseObservableMapTransformers<K, V>());
         this._source = source;
         this._apply = apply;
     }
diff --git a/src/observable/map/BaseObservableMap.ts b/src/observable/map/BaseObservableMap.ts
index 86300439..aa76f641 100644
--- a/src/observable/map/BaseObservableMap.ts
+++ b/src/observable/map/BaseObservableMap.ts
@@ -19,7 +19,7 @@ import {JoinedMap} from "../map/JoinedMap";
 import {MappedMap} from "../map/MappedMap";
 import {FilteredMap} from "../map/FilteredMap";
 import {SortedMapList} from "../list/SortedMapList.js";
-import type {BaseObservableMapDefaults, Mapper, Updater, Comparator, Filter} from "./BaseObservableMapDefaults";
+import type {BaseObservableMapTransformers, Mapper, Updater, Comparator, Filter} from "./BaseObservableMapTransformers";
 
 
 export interface IMapObserver<K, V> {
@@ -30,9 +30,9 @@ export interface IMapObserver<K, V> {
 }
 
 export abstract class BaseObservableMap<K, V> extends BaseObservable<IMapObserver<K, V>> {
-    private _defaults: BaseObservableMapDefaults<K, V>;
+    private _defaults: BaseObservableMapTransformers<K, V>;
 
-    constructor(defaults: BaseObservableMapDefaults<K, V>) {
+    constructor(defaults: BaseObservableMapTransformers<K, V>) {
         super();
         this._defaults = defaults;
     }
diff --git a/src/observable/map/BaseObservableMapDefaults.ts b/src/observable/map/BaseObservableMapTransformers.ts
similarity index 63%
rename from src/observable/map/BaseObservableMapDefaults.ts
rename to src/observable/map/BaseObservableMapTransformers.ts
index 444b8640..3b39587d 100644
--- a/src/observable/map/BaseObservableMapDefaults.ts
+++ b/src/observable/map/BaseObservableMapTransformers.ts
@@ -20,11 +20,26 @@ import {JoinedMap} from "./JoinedMap";
 import {SortedMapList} from "../list/SortedMapList.js";
 
 
-// This class provides implementations of functions that are part of BaseObservableMap.
-// It is kept as its own class in its own file in order to avoid a circular
-// dependency between the classes that extend BaseObservableMap which are
-// instantiated here (i.e. `new JoinedMap()`).
-export class BaseObservableMapDefaults<K, V> {
+// This class provides implementations of functions that transform one BaseObservableMap
+// to another type of Map. It's methods are effectively default implementations of the
+// methods by the same name on BaseObservableMap.
+//
+// It is kept as its own class in its own file in order to avoid circular dependencies
+// which would occur if these method implementations were defined on BaseObservableMap
+// itself. For example, if we attmpted to do the following on BaseObservableMap:
+//
+// class BaseObservableMap<K, V> extends BaseObservable<IMapObserver<K, V>> {
+//   join(...otherMaps: Array<BaseObservableMap<K, V>>): JoinedMap<K, V> {
+//      return new JoinedMap(this.concat(otherMaps));
+//   }
+// }
+//
+// we would end up with a circular dependency between BaseObservableMap and JoinedMap,
+// since BaseObservableMap would need to import JoinedMap for the
+// `return new JoinedMap(this.concat(otherMaps))`, and
+// JoinedMap would need to import BaseObservableMap to do
+// `JoinedMap<K, V> extends BaseObservableMap<K, V>`.
+export class BaseObservableMapTransformers<K, V> {
     join(_this: BaseObservableMap<K, V>, ...otherMaps: Array<BaseObservableMap<K, V>>): JoinedMap<K, V> {
        return new JoinedMap([_this].concat(otherMaps));
     }
diff --git a/src/observable/map/FilteredMap.ts b/src/observable/map/FilteredMap.ts
index 267d0d35..2f3ba9fd 100644
--- a/src/observable/map/FilteredMap.ts
+++ b/src/observable/map/FilteredMap.ts
@@ -16,7 +16,7 @@ limitations under the License.
 
 import {BaseObservableMap} from "./BaseObservableMap";
 import {SubscriptionHandle} from "../BaseObservable";
-import {BaseObservableMapDefaults, Filter} from "./BaseObservableMapDefaults";
+import {BaseObservableMapTransformers, Filter} from "./BaseObservableMapTransformers";
 
 
 export class FilteredMap<K, V> extends BaseObservableMap<K, V> {
@@ -26,7 +26,7 @@ export class FilteredMap<K, V> extends BaseObservableMap<K, V> {
     private _subscription?: SubscriptionHandle;
 
     constructor(source: BaseObservableMap<K, V>, filter: Filter<K, V>) {
-        super(new BaseObservableMapDefaults<K, V>());
+        super(new BaseObservableMapTransformers<K, V>());
         this._source = source;
         this._filter = filter;
     }
diff --git a/src/observable/map/JoinedMap.ts b/src/observable/map/JoinedMap.ts
index b343d22f..f6cb074a 100644
--- a/src/observable/map/JoinedMap.ts
+++ b/src/observable/map/JoinedMap.ts
@@ -15,7 +15,7 @@ limitations under the License.
 */
 
 import {BaseObservableMap} from "./BaseObservableMap";
-import {BaseObservableMapDefaults} from "./BaseObservableMapDefaults";
+import {BaseObservableMapTransformers} from "./BaseObservableMapTransformers";
 import {SubscriptionHandle} from "../BaseObservable";
 
 
@@ -24,7 +24,7 @@ export class JoinedMap<K, V> extends BaseObservableMap<K, V> {
     private _subscriptions?: SourceSubscriptionHandler<K, V>[];
 
     constructor(sources: BaseObservableMap<K, V>[]) {
-        super(new BaseObservableMapDefaults<K, V>());
+        super(new BaseObservableMapTransformers<K, V>());
         this._sources = sources;
     }
 
diff --git a/src/observable/map/LogMap.ts b/src/observable/map/LogMap.ts
index 6db70f01..15f204d2 100644
--- a/src/observable/map/LogMap.ts
+++ b/src/observable/map/LogMap.ts
@@ -15,7 +15,7 @@ limitations under the License.
 */
 
 import {BaseObservableMap} from "./BaseObservableMap";
-import {BaseObservableMapDefaults} from "./BaseObservableMapDefaults";
+import {BaseObservableMapTransformers} from "./BaseObservableMapTransformers";
 import {SubscriptionHandle} from "../BaseObservable";
 import {ILogItem, LabelOrValues} from "../../logging/types";
 import {LogLevel} from "../../logging/LogFilter";
@@ -27,7 +27,7 @@ export class LogMap<K, V> extends BaseObservableMap<K, V> {
     private _log: ILogItem;
 
     constructor(source: BaseObservableMap<K, V>, log: ILogItem) {
-        super(new BaseObservableMapDefaults<K, V>());
+        super(new BaseObservableMapTransformers<K, V>());
         this._source = source;
         this._log = log;
     }
diff --git a/src/observable/map/MappedMap.ts b/src/observable/map/MappedMap.ts
index 72115d84..bd091856 100644
--- a/src/observable/map/MappedMap.ts
+++ b/src/observable/map/MappedMap.ts
@@ -15,7 +15,7 @@ limitations under the License.
 */
 
 import {BaseObservableMap} from "./BaseObservableMap";
-import {BaseObservableMapDefaults, Mapper, Updater} from "./BaseObservableMapDefaults";
+import {BaseObservableMapTransformers, Mapper, Updater} from "./BaseObservableMapTransformers";
 import {SubscriptionHandle} from "../BaseObservable";
 
 
@@ -36,7 +36,7 @@ export class MappedMap<K, V> extends BaseObservableMap<K, V> {
         mapper: Mapper<V>,
         updater?: Updater<V>
     ) {
-        super(new BaseObservableMapDefaults<K, V>());
+        super(new BaseObservableMapTransformers<K, V>());
         this._source = source;
         this._mapper = mapper;
         this._updater = updater;
diff --git a/src/observable/map/ObservableMap.ts b/src/observable/map/ObservableMap.ts
index 9527ffdd..09a73d71 100644
--- a/src/observable/map/ObservableMap.ts
+++ b/src/observable/map/ObservableMap.ts
@@ -15,14 +15,14 @@ limitations under the License.
 */
 
 import {BaseObservableMap} from "./BaseObservableMap";
-import {BaseObservableMapDefaults} from "./BaseObservableMapDefaults";
+import {BaseObservableMapTransformers} from "./BaseObservableMapTransformers";
 
 
 export class ObservableMap<K, V> extends BaseObservableMap<K, V> {
     private readonly _values: Map<K, V>;
 
     constructor(initialValues?: (readonly [K, V])[]) {
-        super(new BaseObservableMapDefaults<K, V>());
+        super(new BaseObservableMapTransformers<K, V>());
         this._values = new Map(initialValues);
     }