diff --git a/action/main.py b/action/main.py
index c59cd8055..ec886d758 100644
--- a/action/main.py
+++ b/action/main.py
@@ -66,9 +66,7 @@ def pip_install(*packages):
 req = ["darker[color,isort]"]
 if VERSION:
     if VERSION.startswith("@"):
-        req[0] = (
-            f"git+https://github.com/akaihola/darker{VERSION}[color,isort]#egg=darker"
-        )
+        req[0] += f"@git+https://github.com/akaihola/darker{VERSION}"
     elif VERSION.startswith(("~", "=", "<", ">")):
         req[0] += VERSION
     else: