diff --git a/src/collection/collection.ts b/src/collection/collection.ts
index 13943b1e..cd9917cc 100644
--- a/src/collection/collection.ts
+++ b/src/collection/collection.ts
@@ -94,7 +94,10 @@ export class Collection<T> {
     filter?: Document,
     options?: CountOptions,
   ): Promise<number> {
-    const pipeline: Document[] = [{ $match: filter }];
+    const pipeline: Document[] = [];
+    if (filter) {
+      pipeline.push({ $match: filter });
+    }
 
     if (typeof options?.skip === "number") {
       pipeline.push({ $skip: options.skip });
diff --git a/tests/cases/03_curd.ts b/tests/cases/03_curd.ts
index a519674f..e7b3b1e0 100644
--- a/tests/cases/03_curd.ts
+++ b/tests/cases/03_curd.ts
@@ -251,6 +251,9 @@ export default function curdTests() {
   testWithClient("testCountDocuments", async (client) => {
     const db = client.database("test");
     const users = db.collection("mongo_test_users");
+    const countAll = await users.countDocuments();
+    assertEquals(countAll, 4);
+
     const count = await users.countDocuments({ username: "many" });
     assertEquals(count, 2);
   });