diff --git a/av1/encoder/encode_strategy.c b/av1/encoder/encode_strategy.c
index 28803a9..793a64b 100644
--- a/av1/encoder/encode_strategy.c
+++ b/av1/encoder/encode_strategy.c
@@ -672,7 +672,8 @@
         for (int idx = i; idx < ref_buffer_stack->lst_stack_size - 1; ++idx)
           ref_buffer_stack->lst_stack[idx] =
               ref_buffer_stack->lst_stack[idx + 1];
-        ref_buffer_stack->lst_stack[i] = INVALID_IDX;
+        ref_buffer_stack->lst_stack[ref_buffer_stack->lst_stack_size - 1] =
+            INVALID_IDX;
         --ref_buffer_stack->lst_stack_size;
       }
     }
@@ -684,7 +685,8 @@
         for (int idx = i; idx < ref_buffer_stack->gld_stack_size - 1; ++idx)
           ref_buffer_stack->gld_stack[idx] =
               ref_buffer_stack->gld_stack[idx + 1];
-        ref_buffer_stack->gld_stack[i] = INVALID_IDX;
+        ref_buffer_stack->gld_stack[ref_buffer_stack->gld_stack_size - 1] =
+            INVALID_IDX;
         --ref_buffer_stack->gld_stack_size;
       }
     }