diff --git a/action/main.py b/action/main.py
index f6814b537..fc5ac6a80 100644
--- a/action/main.py
+++ b/action/main.py
@@ -68,7 +68,9 @@ def pip_install(*packages):
 req = ["darker[color,isort]"]
 if VERSION:
     if VERSION.startswith("@"):
-        req[0] = f"git+https://github.com/akaihola/darker{VERSION}#egg=darker"
+        req[0] = (
+            f"git+https://github.com/akaihola/darker{VERSION}[color,isort]#egg=darker"
+        )
     elif VERSION.startswith(("~", "=", "<", ">")):
         req[0] += VERSION
     else: