diff --git a/.drone.yml b/.drone.yml
index f275d5f..b9efa2a 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -10,6 +10,8 @@ platform:
 
 steps:
   - name: Run unit test
+    environment:
+      PYTHONPATH: .
     commands:
       - python3 tests/main.py
 
@@ -25,6 +27,8 @@ platform:
 
 steps:
   - name: Run unit test
+    environment:
+      PYTHONPATH: .
     commands:
       - python3 tests/main.py
 
@@ -40,6 +44,8 @@ platform:
 
 steps:
   - name: Run unit test
+    environment:
+      PYTHONPATH: .
     commands:
       - python3 tests/main.py
 
@@ -68,6 +74,8 @@ name: docker_python:3.6
 steps:
   - name: Run unit test
     image: python:3.6
+    environment:
+      PYTHONPATH: .
     commands:
       - pip install python-dateutil
       - tests/main.py
@@ -80,6 +88,8 @@ name: docker_python:latest
 steps:
   - name: Run unit test
     image: python:latest
+    environment:
+      PYTHONPATH: .
     commands:
       - pip install python-dateutil
       - python --version