diff --git a/.flowconfig b/.flowconfig
index 4a58bdcde..fd9e98c1e 100644
--- a/.flowconfig
+++ b/.flowconfig
@@ -1,4 +1,8 @@
 [ignore]
+.*/lib/.*
+.*/src/.*
+.*/node_modules/config-chain.*
+.*/node_modules/npmconf.*
 
 [include]
 
diff --git a/src/index.js b/src/index.js
index 67055d9f3..c581212c7 100644
--- a/src/index.js
+++ b/src/index.js
@@ -57,7 +57,7 @@ export default class MongoDBMemoryServer {
       const data = {};
       let tmpDir;
 
-      data.port = await getport(this.opts.port || 27017);
+      data.port = await getport(this.opts.port);
       data.uri = await generateConnectionString(data.port);
       data.storageEngine = this.opts.storageEngine || 'ephemeralForTest';
       if (this.opts.dbPath) {