diff --git a/.github/workflows/pythonpackage.yml b/.github/workflows/pythonpackage.yml
index 574c7be9..defc1596 100644
--- a/.github/workflows/pythonpackage.yml
+++ b/.github/workflows/pythonpackage.yml
@@ -21,17 +21,12 @@ jobs:
       run: |
         python -m pip install --upgrade pip
         pip install -r requirements.txt
-    - name: Lint with flake8
-      run: |
-        pip install flake8
-        # stop the build if there are Python syntax errors or undefined names
-        flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
-        # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
-        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
     - name: install coverage
       run: pip install coverage
     - name: install mypy
       run: pip install mypy
+    - name: install pycodestyle
+      run: pip install pycodestyle
     - name: mypy check
       run: |
         find AerialNavigation -name "*.py" | xargs mypy
@@ -43,7 +38,10 @@ jobs:
         find PathPlanning -name "*.py" | xargs mypy
         find PathTracking -name "*.py" | xargs mypy
         find SLAM -name "*.py" | xargs mypy
+    - name: do diff style check
+      run: bash rundiffstylecheck.sh
     - name: do all unit tests
       run: bash runtests.sh
 
 
+
diff --git a/environment.yml b/environment.yml
index 6866ed93..da1c3c0a 100644
--- a/environment.yml
+++ b/environment.yml
@@ -4,7 +4,7 @@ dependencies:
 - pip
 - matplotlib
 - scipy
-- numpy==1.15
+- numpy
 - pandas
 - coverage
 - pip:
diff --git a/rundiffstylecheck.sh b/rundiffstylecheck.sh
new file mode 100644
index 00000000..627e4a1b
--- /dev/null
+++ b/rundiffstylecheck.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+echo "$(basename $0) start!"
+VERSION=v0.1.3
+wget https://github.com/AtsushiSakai/DiffSentinel/archive/${VERSION}.zip
+unzip ${VERSION}.zip
+./DiffSentinel*/starter.sh HEAD origin/master
+check_result=$?
+rm -rf ${VERSION}.zip DiffSentinel*
+if [[ ${check_result} -ne 0 ]];
+then
+    echo "Error: Your changes contain pycodestyle errors."
+    exit 1
+fi
+echo "$(basename $0) done!"
+exit 0