diff --git a/Makefile b/Makefile
index 447cf1c..ff1585a 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@ MMCFLAGS := --infer-all --no-inform-inferred --warn-unused-imports \
 all: aoc
 
 aoc: $(wildcard *.m)
-	nix shell nixpkgs#mercury -c mmc $(MMCFLAGS) --make aoc
+	mmc $(MMCFLAGS) --make aoc
 
 clean:
 	rm -rf Mercury