diff --git a/packages/metro-file-map/src/watchers/FSEventsWatcher.js b/packages/metro-file-map/src/watchers/FSEventsWatcher.js
index a0e9d7f70..0b11ddf07 100644
--- a/packages/metro-file-map/src/watchers/FSEventsWatcher.js
+++ b/packages/metro-file-map/src/watchers/FSEventsWatcher.js
@@ -40,12 +40,6 @@ const DELETE_EVENT = 'delete';
 const ADD_EVENT = 'add';
 const ALL_EVENT = 'all';
 
-type FsEventsWatcherEvent =
-  | typeof CHANGE_EVENT
-  | typeof DELETE_EVENT
-  | typeof ADD_EVENT
-  | typeof ALL_EVENT;
-
 /**
  * Export `FSEventsWatcher` class.
  * Watches `dir`.
@@ -168,10 +162,10 @@ export default class FSEventsWatcher extends EventEmitter {
       };
 
       if (this._tracked.has(filepath)) {
-        this._emit(CHANGE_EVENT, relativePath, metadata);
+        this._emit({event: CHANGE_EVENT, relativePath, metadata});
       } else {
         this._tracked.add(filepath);
-        this._emit(ADD_EVENT, relativePath, metadata);
+        this._emit({event: ADD_EVENT, relativePath, metadata});
       }
     } catch (error) {
       if (error?.code !== 'ENOENT') {
@@ -184,7 +178,7 @@ export default class FSEventsWatcher extends EventEmitter {
         return;
       }
 
-      this._emit(DELETE_EVENT, relativePath);
+      this._emit({event: DELETE_EVENT, relativePath});
       this._tracked.delete(filepath);
     }
   }
@@ -192,13 +186,23 @@ export default class FSEventsWatcher extends EventEmitter {
   /**
    * Emit events.
    */
-  _emit(
-    type: FsEventsWatcherEvent,
-    file: string,
-    metadata?: ChangeEventMetadata,
-  ) {
-    this.emit(type, file, this.root, metadata);
-    this.emit(ALL_EVENT, type, file, this.root, metadata);
+  _emit({
+    event,
+    relativePath,
+    metadata,
+  }:
+    | {
+        event: 'change' | 'add',
+        relativePath: string,
+        metadata: ChangeEventMetadata,
+      }
+    | {
+        event: 'delete',
+        relativePath: string,
+        metadata?: void,
+      }) {
+    this.emit(event, relativePath, this.root, metadata);
+    this.emit(ALL_EVENT, event, relativePath, this.root, metadata);
   }
 
   getPauseReason(): ?string {
diff --git a/packages/metro-file-map/src/watchers/NodeWatcher.js b/packages/metro-file-map/src/watchers/NodeWatcher.js
index 183d99b1d..59e9e556d 100644
--- a/packages/metro-file-map/src/watchers/NodeWatcher.js
+++ b/packages/metro-file-map/src/watchers/NodeWatcher.js
@@ -298,19 +298,27 @@ module.exports = class NodeWatcher extends EventEmitter {
           path.resolve(this.root, relativePath),
           (dir, stats) => {
             if (this._watchdir(dir)) {
-              this._emitEvent(ADD_EVENT, path.relative(this.root, dir), {
-                modifiedTime: stats.mtime.getTime(),
-                size: stats.size,
-                type: 'd',
+              this._emitEvent({
+                event: ADD_EVENT,
+                relativePath: path.relative(this.root, dir),
+                metadata: {
+                  modifiedTime: stats.mtime.getTime(),
+                  size: stats.size,
+                  type: 'd',
+                },
               });
             }
           },
           (file, stats) => {
             if (this._register(file, 'f')) {
-              this._emitEvent(ADD_EVENT, path.relative(this.root, file), {
-                modifiedTime: stats.mtime.getTime(),
-                size: stats.size,
-                type: 'f',
+              this._emitEvent({
+                event: ADD_EVENT,
+                relativePath: path.relative(this.root, file),
+                metadata: {
+                  modifiedTime: stats.mtime.getTime(),
+                  size: stats.size,
+                  type: 'f',
+                },
               });
             }
           },
@@ -338,10 +346,10 @@ module.exports = class NodeWatcher extends EventEmitter {
           type,
         };
         if (registered) {
-          this._emitEvent(CHANGE_EVENT, relativePath, metadata);
+          this._emitEvent({event: CHANGE_EVENT, relativePath, metadata});
         } else {
           if (this._register(fullPath, type)) {
-            this._emitEvent(ADD_EVENT, relativePath, metadata);
+            this._emitEvent({event: ADD_EVENT, relativePath, metadata});
           }
         }
       }
@@ -353,7 +361,7 @@ module.exports = class NodeWatcher extends EventEmitter {
       this._unregister(fullPath);
       this._unregisterDir(fullPath);
       if (registered) {
-        this._emitEvent(DELETE_EVENT, relativePath);
+        this._emitEvent({event: DELETE_EVENT, relativePath});
       }
       await this._stopWatching(fullPath);
     }
@@ -366,10 +374,24 @@ module.exports = class NodeWatcher extends EventEmitter {
    *
    * See also note above for DEBOUNCE_MS.
    */
-  _emitEvent(type: string, file: string, metadata?: ChangeEventMetadata) {
-    const key = type + '-' + file;
-    const addKey = ADD_EVENT + '-' + file;
-    if (type === CHANGE_EVENT && this._changeTimers.has(addKey)) {
+  _emitEvent({
+    event,
+    relativePath,
+    metadata,
+  }:
+    | {
+        event: 'change' | 'add',
+        relativePath: string,
+        metadata: ChangeEventMetadata,
+      }
+    | {
+        event: 'delete',
+        relativePath: string,
+        metadata?: void,
+      }) {
+    const key = event + '-' + relativePath;
+    const addKey = ADD_EVENT + '-' + relativePath;
+    if (event === CHANGE_EVENT && this._changeTimers.has(addKey)) {
       // Ignore the change event that is immediately fired after an add event.
       // (This happens on Linux).
       return;
@@ -382,7 +404,7 @@ module.exports = class NodeWatcher extends EventEmitter {
       key,
       setTimeout(() => {
         this._changeTimers.delete(key);
-        this._rawEmitEvent(type, file, metadata);
+        this._rawEmitEvent(event, relativePath, metadata);
       }, DEBOUNCE_MS),
     );
   }
diff --git a/packages/metro-file-map/src/watchers/WatchmanWatcher.js b/packages/metro-file-map/src/watchers/WatchmanWatcher.js
index 3a0d57133..ee2938d9d 100644
--- a/packages/metro-file-map/src/watchers/WatchmanWatcher.js
+++ b/packages/metro-file-map/src/watchers/WatchmanWatcher.js
@@ -272,7 +272,7 @@ export default class WatchmanWatcher extends EventEmitter {
     }
 
     if (!exists) {
-      self._emitEvent(DELETE_EVENT, relativePath, self.root);
+      self._emitEvent({event: DELETE_EVENT, relativePath});
     } else {
       const eventType = isNew ? ADD_EVENT : CHANGE_EVENT;
       invariant(
@@ -290,10 +290,14 @@ export default class WatchmanWatcher extends EventEmitter {
         !(type === 'd' && eventType === CHANGE_EVENT)
       ) {
         const mtime = Number(mtime_ms);
-        self._emitEvent(eventType, relativePath, self.root, {
-          modifiedTime: mtime !== 0 ? mtime : null,
-          size,
-          type,
+        self._emitEvent({
+          event: eventType,
+          relativePath,
+          metadata: {
+            modifiedTime: mtime !== 0 ? mtime : null,
+            size,
+            type,
+          },
         });
       }
     }
@@ -302,14 +306,23 @@ export default class WatchmanWatcher extends EventEmitter {
   /**
    * Dispatches the event.
    */
-  _emitEvent(
-    eventType: string,
-    filepath: string,
-    root: string,
-    changeMetadata?: ChangeEventMetadata,
-  ) {
-    this.emit(eventType, filepath, root, changeMetadata);
-    this.emit(ALL_EVENT, eventType, filepath, root, changeMetadata);
+  _emitEvent({
+    event,
+    relativePath,
+    metadata,
+  }:
+    | {
+        event: 'change' | 'add',
+        relativePath: string,
+        metadata: ChangeEventMetadata,
+      }
+    | {
+        event: 'delete',
+        relativePath: string,
+        metadata?: void,
+      }) {
+    this.emit(event, relativePath, this.root, metadata);
+    this.emit(ALL_EVENT, event, relativePath, this.root, metadata);
   }
 
   /**