diff --git a/start_linux.sh b/start_linux.sh
index c74f1272..e2b00558 100755
--- a/start_linux.sh
+++ b/start_linux.sh
@@ -1,5 +1,10 @@
 #!/usr/bin/env bash
 
+# environment isolation
+export PYTHONNOUSERSITE=1
+unset PYTHONPATH
+unset PYTHONHOME
+
 cd "$(dirname "${BASH_SOURCE[0]}")"
 
 # Portable install case
@@ -61,10 +66,6 @@ if [ ! -e "$INSTALL_ENV_DIR/bin/python" ]; then
     exit
 fi
 
-# environment isolation
-export PYTHONNOUSERSITE=1
-unset PYTHONPATH
-unset PYTHONHOME
 export CUDA_PATH="$INSTALL_ENV_DIR"
 export CUDA_HOME="$CUDA_PATH"
 
diff --git a/start_macos.sh b/start_macos.sh
index 7a060ba6..bff11bc1 100755
--- a/start_macos.sh
+++ b/start_macos.sh
@@ -1,5 +1,10 @@
 #!/bin/bash
 
+# environment isolation
+export PYTHONNOUSERSITE=1
+unset PYTHONPATH
+unset PYTHONHOME
+
 cd "$(dirname "${BASH_SOURCE[0]}")"
 
 # Portable install case
@@ -61,10 +66,6 @@ if [ ! -e "$INSTALL_ENV_DIR/bin/python" ]; then
     exit
 fi
 
-# environment isolation
-export PYTHONNOUSERSITE=1
-unset PYTHONPATH
-unset PYTHONHOME
 export CUDA_PATH="$INSTALL_ENV_DIR"
 export CUDA_HOME="$CUDA_PATH"
 
diff --git a/start_windows.bat b/start_windows.bat
index 1616ee27..f5e66ec2 100755
--- a/start_windows.bat
+++ b/start_windows.bat
@@ -1,6 +1,11 @@
 @echo off
 setlocal enabledelayedexpansion
 
+@rem environment isolation
+set PYTHONNOUSERSITE=1
+set PYTHONPATH=
+set PYTHONHOME=
+
 cd /D "%~dp0"
 
 @rem Portable install case
@@ -87,10 +92,6 @@ if not exist "%INSTALL_ENV_DIR%" (
 @rem check if conda environment was actually created
 if not exist "%INSTALL_ENV_DIR%\python.exe" ( echo. && echo Conda environment is empty. && goto end )
 
-@rem environment isolation
-set PYTHONNOUSERSITE=1
-set PYTHONPATH=
-set PYTHONHOME=
 set "CUDA_PATH=%INSTALL_ENV_DIR%"
 set "CUDA_HOME=%CUDA_PATH%"