diff --git a/packages/pigeon/CHANGELOG.md b/packages/pigeon/CHANGELOG.md
index 4d0ef22ebb44..3763675dc3f6 100644
--- a/packages/pigeon/CHANGELOG.md
+++ b/packages/pigeon/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.1.9
+
+* Fixed bug where executing pigeon without arguments would crash (introduced in 0.1.8).
+
 ## 0.1.8
 
 * Started spawning pigeon_lib in an isolate instead of a subprocess.  The
diff --git a/packages/pigeon/bin/pigeon.dart b/packages/pigeon/bin/pigeon.dart
index 72497a87cd5e..441595617646 100644
--- a/packages/pigeon/bin/pigeon.dart
+++ b/packages/pigeon/bin/pigeon.dart
@@ -10,14 +10,15 @@ import 'package:pigeon/pigeon_lib.dart';
 
 Future<void> main(List<String> args) async {
   final PigeonOptions opts = Pigeon.parseArgs(args);
-  assert(opts.input != null);
-  final String rawInputPath = opts.input;
   final Directory tempDir = Directory.systemTemp.createTempSync();
-  final String absInputPath = File(rawInputPath).absolute.path;
-  final String relInputPath = path.relative(absInputPath, from: tempDir.path);
 
-  final String importLine =
-      (opts.input != null) ? 'import \'$relInputPath\';\n' : '';
+  String importLine = '';
+  if (opts.input != null) {
+    final String rawInputPath = opts.input;
+    final String absInputPath = File(rawInputPath).absolute.path;
+    final String relInputPath = path.relative(absInputPath, from: tempDir.path);
+    importLine = 'import \'$relInputPath\';\n';
+  }
   final String code = """$importLine
 import 'dart:io';
 import 'dart:isolate';
diff --git a/packages/pigeon/lib/generator_tools.dart b/packages/pigeon/lib/generator_tools.dart
index 940fa19d0060..05a9c6795b7e 100644
--- a/packages/pigeon/lib/generator_tools.dart
+++ b/packages/pigeon/lib/generator_tools.dart
@@ -8,7 +8,7 @@ import 'dart:mirrors';
 import 'ast.dart';
 
 /// The current version of pigeon.
-const String pigeonVersion = '0.1.8';
+const String pigeonVersion = '0.1.9';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {
diff --git a/packages/pigeon/pubspec.yaml b/packages/pigeon/pubspec.yaml
index d2ff73ccc37c..c9324df0e472 100644
--- a/packages/pigeon/pubspec.yaml
+++ b/packages/pigeon/pubspec.yaml
@@ -1,5 +1,5 @@
 name: pigeon
-version: 0.1.8
+version: 0.1.9
 description: Code generator tool to make communication between Flutter and the host platform type-safe and easier.
 homepage: https://github.com/flutter/packages/tree/master/packages/pigeon
 dependencies:
diff --git a/packages/pigeon/run_tests.sh b/packages/pigeon/run_tests.sh
index 9650f6d4d5bf..15e4093151fe 100755
--- a/packages/pigeon/run_tests.sh
+++ b/packages/pigeon/run_tests.sh
@@ -73,6 +73,11 @@ test_pigeon_android() {
 pub get
 pub run test test/
 
+###############################################################################
+# Execute without arguments test
+###############################################################################
+pub run pigeon
+
 ###############################################################################
 # Compilation tests (Code is generated and compiled)
 ###############################################################################