diff --git a/dom/fs/api/FileSystemHandle.cpp b/dom/fs/api/FileSystemHandle.cpp
index 65680d59c7b0..c752bdc61452 100644
--- a/dom/fs/api/FileSystemHandle.cpp
+++ b/dom/fs/api/FileSystemHandle.cpp
@@ -103,7 +103,11 @@ already_AddRefed<Promise> FileSystemHandle::IsSameEntry(
     return nullptr;
   }
 
-  promise->MaybeReject(NS_ERROR_NOT_IMPLEMENTED);
+  // Handles the case of "dir = createdir foo; removeEntry(foo); file =
+  // createfile foo; issameentry(dir, file)"
+  const bool result = mMetadata.entryId().Equals(aOther.mMetadata.entryId()) &&
+                      Kind() == aOther.Kind();
+  promise->MaybeResolve(result);
 
   return promise.forget();
 }
diff --git a/dom/fs/test/gtest/api/TestFileSystemHandle.cpp b/dom/fs/test/gtest/api/TestFileSystemHandle.cpp
index adb653c317e5..a176bfc7982b 100644
--- a/dom/fs/test/gtest/api/TestFileSystemHandle.cpp
+++ b/dom/fs/test/gtest/api/TestFileSystemHandle.cpp
@@ -96,11 +96,11 @@ TEST_F(TestFileSystemHandle, isDifferentEntry) {
   RefPtr<Promise> promise = dirHandle->IsSameEntry(*fileHandle, rv);
   ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
   ASSERT_TRUE(promise);
-  ASSERT_EQ(Promise::PromiseState::Rejected, promise->State());
+  ASSERT_EQ(Promise::PromiseState::Resolved, promise->State());
 
   nsString result;
   ASSERT_NSEQ(NS_OK, GetAsString(promise, result));
-  ASSERT_STREQ(u"NS_ERROR_NOT_IMPLEMENTED"_ns, result);
+  ASSERT_STREQ(u"false"_ns, result);
 }
 
 TEST_F(TestFileSystemHandle, isSameEntry) {
@@ -111,11 +111,11 @@ TEST_F(TestFileSystemHandle, isSameEntry) {
   RefPtr<Promise> promise = fileHandle->IsSameEntry(*fileHandle, rv);
   ASSERT_TRUE(rv.ErrorCodeIs(NS_OK));
   ASSERT_TRUE(promise);
-  ASSERT_EQ(Promise::PromiseState::Rejected, promise->State());
+  ASSERT_EQ(Promise::PromiseState::Resolved, promise->State());
 
   nsString result;
   ASSERT_NSEQ(NS_OK, GetAsString(promise, result));
-  ASSERT_STREQ(u"NS_ERROR_NOT_IMPLEMENTED"_ns, result);
+  ASSERT_STREQ(u"true"_ns, result);
 }
 
 }  // namespace mozilla::dom::fs::test