diff --git a/environment_win.yml b/environment_win.yml
index 3da9d77cac..60774b822c 100644
--- a/environment_win.yml
+++ b/environment_win.yml
@@ -8,7 +8,6 @@ dependencies:
   - re2c
   - toml
   - zlib
-  - flex
   - cmake
   - ninja
   - numpy