diff --git a/lib.sh b/lib.sh
index 49331a9..02a7472 100644
--- a/lib.sh
+++ b/lib.sh
@@ -3,29 +3,31 @@
 # 
 lib_get_esptool_command() {
     WIN_PYTHON="python"
-    if command -v esptool.py &> /dev/null
+    MAC_ESPTOOL="esptool"
+    if command -v $MAC_ESPTOOL &> /dev/null
     then
-        echo "esptool.py"
+        echo "$MAC_ESPTOOL"
+        return
     else
-    if ! command -v $WIN_PYTHON &> /dev/null
-    then
-        $WIN_PYTHON
-        echo "エラー：Pythonコマンドを使用するため、まずPythonをインストールしてください。"
-        echo "esptool.py nor $WIN_PYTHON could not be found. Please install it first."
-        exit 1
-    else
-        # check if esptool is installed as a module
-        if $WIN_PYTHON -m esptool --help &> /dev/null
+        if ! command -v $WIN_PYTHON &> /dev/null
         then
-            echo "$WIN_PYTHON -m esptool"
-            return
+            $WIN_PYTHON
+            echo "エラー：Pythonコマンドを使用するため、まずPythonをインストールしてください。"
+            echo "$MAC_ESPTOOL nor $WIN_PYTHON could not be found. Please install it first."
+            exit 1
         else
-            $WIN_PYTHON -m pip install --upgrade pip
-            $WIN_PYTHON -m pip install esptool --no-warn-script-location
-            return
+            # check if esptool is installed as a module
+            if $WIN_PYTHON -m esptool --help &> /dev/null
+            then
+                echo "$WIN_PYTHON -m esptool"
+                return
+            else
+                $WIN_PYTHON -m pip install --upgrade pip
+                $WIN_PYTHON -m pip install esptool --no-warn-script-location
+                return
+            fi
+            echo "$WIN_PYTHON -m esptool"
         fi
-        echo "$WIN_PYTHON -m esptool"
-    fi
     fi
 }