diff --git a/src/vm/mem/mod.rs b/src/vm/mem/mod.rs
index 61fbf20..f20f478 100644
--- a/src/vm/mem/mod.rs
+++ b/src/vm/mem/mod.rs
@@ -114,9 +114,7 @@ fn collect_garbage(
     for stack_value in stack {
         match stack_value {
             DvmValue::Object(gc) => {
-                if gc.color() == GcColor::White {
-                    gray_stack.push(gc.clone());
-                }
+                gray_stack.push(gc.clone());
             }
             _ => {}
         }
@@ -126,7 +124,9 @@ fn collect_garbage(
         for field in current.data().borrow().fields() {
             match field {
                 DvmValue::Object(object) => {
-                    gray_stack.push(object.clone());
+                    if object.color() == GcColor::White {
+                        gray_stack.push(object.clone());
+                    }
                 }
                 _ => {}
             }