diff --git a/passes/opt/peepopt.cc b/passes/opt/peepopt.cc
index d283cfe82..cb6174d66 100644
--- a/passes/opt/peepopt.cc
+++ b/passes/opt/peepopt.cc
@@ -121,7 +121,7 @@ struct PeepoptPass : public Pass {
 					pm.run_shiftmul_left();
 					pm.run_muldiv();
 					pm.run_muldiv_c();
-					// pm.run_sub_neg();
+					pm.run_sub_neg();
 					if (muxorder)
 						pm.run_muxorder();
 				}