diff --git a/src/core/gc.c b/src/core/gc.c
index f9de7d42..6a1af02b 100644
--- a/src/core/gc.c
+++ b/src/core/gc.c
@@ -549,7 +549,6 @@ void janet_clear_memory(void) {
 #endif
     JanetGCObject *current = janet_vm.blocks;
     while (NULL != current) {
-        current->flags |= JANET_MEM_USEAFTERFREE;
         janet_deinit_block(current);
         JanetGCObject *next = current->data.next;
         gc_free_gcobj(current);
diff --git a/src/core/gc.h b/src/core/gc.h
index 151a2cc0..175caeba 100644
--- a/src/core/gc.h
+++ b/src/core/gc.h
@@ -38,7 +38,7 @@
 #define janet_gc_settype(m, t) ((janet_gc_header(m)->flags |= (0xFF & (t))))
 #define janet_gc_type(m) (janet_gc_header(m)->flags & 0xFF)
 
-#define janet_gc_mark(m) do (janet_gc_header(m)->flags |= JANET_MEM_REACHABLE)
+#define janet_gc_mark(m) (janet_gc_header(m)->flags |= JANET_MEM_REACHABLE)
 #define janet_gc_reachable(m) (janet_gc_header(m)->flags & JANET_MEM_REACHABLE)
 
 /* Memory types for the GC. Different from JanetType to include funcenv and funcdef. */