diff --git a/Makefile b/Makefile
index 6d84b2b..5676980 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-CABALFLAGS ?= --verbose=0 --jobs
+CABALFLAGS ?= --verbose=0 --jobs -O
 
 DATADIR  := data
 TMPDIR   := _tmp