-#ifndef PARALLEL_GC
-#define scavenge_block(a) scavenge_block1(a)
-#define evacuate(a) evacuate1(a)
-#define recordMutableGen_GC(a,b) recordMutableGen(a,b)
+#if defined(THREADED_RTS) && !defined(PARALLEL_GC)
+# define scavenge_block(a) scavenge_block1(a)
+# define evacuate(a) evacuate1(a)
+# define recordMutableGen_GC(a,b) recordMutableGen(a,b)