diff --git a/dist/npmci.test.js b/dist/npmci.test.js
index 11ee055..a234f46 100644
--- a/dist/npmci.test.js
+++ b/dist/npmci.test.js
@@ -24,7 +24,12 @@ exports.test = (versionArg) => __awaiter(this, void 0, void 0, function* () {
 });
 let npmDependencies = () => __awaiter(this, void 0, void 0, function* () {
     plugins.beautylog.info('now installing dependencies:');
-    yield npmci_bash_1.bash('npm install');
+    if (yield npmci_bash_1.yarnAvailable.promise) {
+        yield npmci_bash_1.bash('yarn install');
+    }
+    else {
+        yield npmci_bash_1.bash('npm install');
+    }
 });
 let npmTest = () => __awaiter(this, void 0, void 0, function* () {
     plugins.beautylog.info('now starting tests:');
@@ -35,4 +40,4 @@ let testDocker = () => __awaiter(this, void 0, void 0, function* () {
         .then(NpmciBuildDocker.pullDockerfileImages)
         .then(NpmciBuildDocker.testDockerfiles);
 });
-//# sourceMappingURL=data:application/json;base64,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
\ No newline at end of file
+//# sourceMappingURL=data:application/json;base64,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
\ No newline at end of file
diff --git a/ts/npmci.test.ts b/ts/npmci.test.ts
index cddd102..dda0140 100644
--- a/ts/npmci.test.ts
+++ b/ts/npmci.test.ts
@@ -1,5 +1,5 @@
 import * as plugins from './npmci.plugins'
-import { bash } from './npmci.bash'
+import { bash, yarnAvailable } from './npmci.bash'
 import { install } from './npmci.install'
 import * as env from './npmci.env'
 import * as NpmciBuildDocker from './npmci.build.docker'
@@ -14,9 +14,13 @@ export let test = async (versionArg): Promise<void> => {
   }
 }
 
-let npmDependencies = async ():Promise <void> => {
+let npmDependencies = async (): Promise<void> => {
   plugins.beautylog.info('now installing dependencies:')
-  await bash('npm install')
+  if (await yarnAvailable.promise) {
+    await bash('yarn install')
+  } else {
+    await bash('npm install')
+  }
 }
 
 let npmTest = async (): Promise<void> => {