diff --git a/news/2 Fixes/5496.md b/news/2 Fixes/5496.md
new file mode 100644
index 000000000000..35475ce66ad9
--- /dev/null
+++ b/news/2 Fixes/5496.md	
@@ -0,0 +1,2 @@
+Add dev flag to poetry installer.
+(thanks [Yan Pashkovsky](https://github.com/Yanpas))
diff --git a/src/client/common/installer/poetryInstaller.ts b/src/client/common/installer/poetryInstaller.ts
index 7b7742e0e35f..75809c11796e 100644
--- a/src/client/common/installer/poetryInstaller.ts
+++ b/src/client/common/installer/poetryInstaller.ts
@@ -61,7 +61,7 @@ export class PoetryInstaller extends ModuleInstaller implements IModuleInstaller
     protected async getExecutionInfo(moduleName: string, resource?: Uri): Promise<ExecutionInfo> {
         const execPath = this.configurationService.getSettings(resource).poetryPath;
         return {
-            args: ['add', moduleName],
+            args: ['add', '--dev', moduleName],
             execPath
         };
     }
diff --git a/src/test/common/installer/poetryInstaller.unit.test.ts b/src/test/common/installer/poetryInstaller.unit.test.ts
index 6d19bd102eef..4517c4da62b3 100644
--- a/src/test/common/installer/poetryInstaller.unit.test.ts
+++ b/src/test/common/installer/poetryInstaller.unit.test.ts
@@ -120,6 +120,6 @@ suite('Module Installer - Poetry', () => {
 
         const info = await poetryInstaller.getExecutionInfo('something', uri);
 
-        assert.deepEqual(info, { args: ['add', 'something'], execPath: 'poetry path' });
+        assert.deepEqual(info, { args: ['add', '--dev', 'something'], execPath: 'poetry path' });
     });
 });