diff --git a/src/cmd/5c/reg.c b/src/cmd/5c/reg.c
index 7cd880b9bf..c6d760c509 100644
--- a/src/cmd/5c/reg.c
+++ b/src/cmd/5c/reg.c
@@ -66,12 +66,6 @@ rcmp(const void *a1, const void *a2)
 void
 regopt(Prog *p)
 {
-	USED(p);
-	// TODO(kaib): optimizer disabled because it smashes R8 when running out of registers
-	// the disable is unconventionally here because the call is in common code shared by 5c/6c/8c
-	return;
-
-#ifdef	NOTDEF
 	Reg *r, *r1, *r2;
 	Prog *p1;
 	int i, z;
@@ -500,7 +494,6 @@ brk:
 		r1->link = freer;
 		freer = firstr;
 	}
-#endif
 }
 
 void