diff --git a/gc.c b/gc.c
index 85fd2869ff7a29..5a64d2d59c49e3 100644
--- a/gc.c
+++ b/gc.c
@@ -11210,19 +11210,26 @@ gc_set_flags_start(rb_objspace_t *objspace, unsigned int reason, unsigned int *d
     objspace->flags.immediate_sweep = !!(reason & GPR_FLAG_IMMEDIATE_SWEEP);
 
     objspace->flags.during_global_gc = !!(reason & GPR_FLAG_GLOBAL);
-
-    /* Explicitly enable compaction (GC.compact) */
-    if (*do_full_mark && ruby_enable_autocompact) {
-        objspace->flags.during_compacting = TRUE;
-    }
-    else {
-        objspace->flags.during_compacting = !!(reason & GPR_FLAG_COMPACT);
-    }
 }
 
 static void
 gc_set_flags_finish(rb_objspace_t *objspace, unsigned int reason, unsigned int *do_full_mark, unsigned int *immediate_mark)
 {
+    if (!heap_allocated_pages) return FALSE; /* heap is not ready */
+    if (!(reason & GPR_FLAG_METHOD) && !ready_to_gc(objspace)) return TRUE; /* GC is not allowed */
+
+    GC_ASSERT(gc_mode(objspace) == gc_mode_none);
+    GC_ASSERT(!is_lazy_sweeping(objspace));
+    GC_ASSERT(!is_incremental_marking(objspace));
+
+    unsigned int lock_lev;
+    gc_enter(objspace, gc_enter_event_start, &lock_lev);
+
+#if RGENGC_CHECK_MODE >= 2
+    gc_verify_internal_consistency(objspace);
+#endif
+
+>>>>>>> 7835ebce97a6e6132d2bc7bdbef115f3f47cc6c2
     if (ruby_gc_stressful) {
         int flag = FIXNUM_P(ruby_gc_stress_mode) ? FIX2INT(ruby_gc_stress_mode) : 0;
 
@@ -11256,6 +11263,14 @@ gc_set_flags_finish(rb_objspace_t *objspace, unsigned int reason, unsigned int *
         objspace->flags.during_incremental_marking = *do_full_mark;
     }
 
+    /* Explicitly enable compaction (GC.compact) */
+    if (do_full_mark && ruby_enable_autocompact) {
+        objspace->flags.during_compacting = TRUE;
+    }
+    else {
+        objspace->flags.during_compacting = !!(reason & GPR_FLAG_COMPACT);
+    }
+
     if (!GC_ENABLE_LAZY_SWEEP || objspace->flags.dont_incremental) {
         objspace->flags.immediate_sweep = TRUE;
     }