diff --git a/Makefile b/Makefile
index afa72fe7d2..0856e1b52f 100644
--- a/Makefile
+++ b/Makefile
@@ -132,11 +132,9 @@ clean-local:
 	rm -rf repos
 
 check-merges-reproducibility:
-	@echo "Running replay_merge for each idx in parallel..."
+	@echo "Running replay_merge for each idx in parallel using GNU Parallel..."
 	@set -e; \
-	tail -n +2 $(CSV_RESULTS) | awk -F, '{print $$1}' | while read idx; do \
-		python3 src/python/replay_merge.py --merges_csv $(CSV_RESULTS) -delete_workdir --idx $$idx; \
-	done
+	tail -n +2 $(CSV_RESULTS) | awk -F, '{print $$1}' | parallel -j 100% --bar python3 src/python/replay_merge.py --merges_csv $(CSV_RESULTS) --delete_workdir --idx {}
 
 protect-repos:
 	find repos -mindepth 1 -type d -exec chmod a-w {} +