diff --git a/.travis.yml b/.travis.yml
index 04de0b4..e1f9e07 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,7 +7,7 @@ dart:
 dart_task:
   - test
   - dartfmt
-  - dartanalyzer
+  - dartanalyzer: --fatal-infos --fatal-warnings .
 
 # Only building master means that we don't run two builds for each pull request.
 branches:
diff --git a/example/example.dart b/example/example.dart
index 4812a26..d0c47c1 100644
--- a/example/example.dart
+++ b/example/example.dart
@@ -26,7 +26,7 @@ main(List<String> args) {
   var port = int.parse(results['port'] as String);
   var standalone = results['standalone'] as bool;
 
-  if (results.rest.length > 0) {
+  if (results.rest.isNotEmpty) {
     print('Got unexpected arguments: "${results.rest.join(' ')}".\n\nUsage:\n');
     print(parser.usage);
     exit(1);
diff --git a/example/src/examples/cow_repository.dart b/example/src/examples/cow_repository.dart
index 4d86b5b..e061375 100644
--- a/example/src/examples/cow_repository.dart
+++ b/example/src/examples/cow_repository.dart
@@ -66,7 +66,7 @@ class CopyAndWriteRepository extends PackageRepository {
         .where((pv) => pv.versionString == version)
         .toList()
         .then((List<PackageVersion> versions) {
-      if (versions.length >= 1) return versions.first;
+      if (versions.isNotEmpty) return versions.first;
       return null;
     });
   }
diff --git a/example/src/examples/file_repository.dart b/example/src/examples/file_repository.dart
index d35eeab..b61968b 100644
--- a/example/src/examples/file_repository.dart
+++ b/example/src/examples/file_repository.dart
@@ -49,7 +49,7 @@ class FileRepository extends PackageRepository {
         .where((pv) => pv.versionString == version)
         .toList()
         .then((List<PackageVersion> versions) {
-      if (versions.length >= 1) return versions.first;
+      if (versions.isNotEmpty) return versions.first;
       return null;
     });
   }
diff --git a/example/src/examples/http_proxy_repository.dart b/example/src/examples/http_proxy_repository.dart
index 8ba1df8..735ed28 100644
--- a/example/src/examples/http_proxy_repository.dart
+++ b/example/src/examples/http_proxy_repository.dart
@@ -48,7 +48,7 @@ class HttpProxyRepository extends PackageRepository {
         .where((v) => v.packageName == package && v.versionString == version)
         .toList()
         .then((List<PackageVersion> versions) {
-      if (versions.length >= 1) return versions.first;
+      if (versions.isNotEmpty) return versions.first;
       return null;
     });
   }
diff --git a/lib/shelf_pubserver.dart b/lib/shelf_pubserver.dart
index 12a3ef7..a11a9ae 100644
--- a/lib/shelf_pubserver.dart
+++ b/lib/shelf_pubserver.dart
@@ -240,7 +240,7 @@ class ShelfPubServer {
     }
 
     var packageVersions = await repository.versions(package).toList();
-    if (packageVersions.length == 0) {
+    if (packageVersions.isEmpty) {
       return new shelf.Response.notFound(null);
     }
 
@@ -416,7 +416,7 @@ class ShelfPubServer {
 
   Future<shelf.Response> _addUploader(String package, String body) async {
     var parts = body.split('=');
-    if (parts.length == 2 && parts[0] == 'email' && parts[1].length > 0) {
+    if (parts.length == 2 && parts[0] == 'email' && parts[1].isNotEmpty) {
       try {
         var user = Uri.decodeQueryComponent(parts[1]);
         await repository.addUploader(package, user);