diff --git a/README.md b/README.md
index 6a0a478..b82c4da 100644
--- a/README.md
+++ b/README.md
@@ -144,7 +144,7 @@ experiment-llm/
 
 ## Definition of done (iteration 1)
 
-- [ ] Environment reproducible with `pip install -r requirements.txt`; dataset downloaded and hashed
+- [x] Environment reproducible with `pip install -r requirements.txt`; dataset downloaded and hashed
 - [ ] BPE tokenizer trains, round-trips, and is saved to disk
 - [ ] Corpus encoded to binary token files
 - [ ] Model builds; parameter count matches the estimate