diff --git a/a8/fifobuffer.cc b/a8/fifobuffer.cc
index 79351d8..4a26277 100644
--- a/a8/fifobuffer.cc
+++ b/a8/fifobuffer.cc
@@ -44,6 +44,21 @@ namespace a8
             return (char*)malloc(len);
         } else {
             size_t index = GetIndex(real_len);
+
+            list_head* free_node = nullptr;
+            {
+                lock_.lock();
+                free_node = &free_list_[index];
+                if (list_empty(free_node)) {
+                    free_node = nullptr;
+                } else {
+                    list_del(free_node);
+                }
+                lock_.unlock();
+            }
+            if (free_node) {
+                return (char*)free_node + sizeof(BufHead);
+            }
         }
     }
 
@@ -53,25 +68,25 @@ namespace a8
 
     size_t FifoBuffer::GetIndex(size_t size)
     {
-        if (size <= 128 * std::pow(2, 0)) {
+        if (size <= BASE_BLOCK_SIZE * std::pow(2, 0)) {
             return 0;
-        } else if (size <= 128 * std::pow(2, 1)) {
+        } else if (size <= BASE_BLOCK_SIZE * std::pow(2, 1)) {
             return 1;
-        } else if (size <= 128 * std::pow(2, 2)) {
+        } else if (size <= BASE_BLOCK_SIZE * std::pow(2, 2)) {
             return 2;
-        } else if (size <= 128 * std::pow(2, 3)) {
+        } else if (size <= BASE_BLOCK_SIZE * std::pow(2, 3)) {
             return 3;
-        } else if (size <= 128 * std::pow(2, 4)) {
+        } else if (size <= BASE_BLOCK_SIZE * std::pow(2, 4)) {
             return 4;
-        } else if (size <= 128 * std::pow(2, 5)) {
+        } else if (size <= BASE_BLOCK_SIZE * std::pow(2, 5)) {
             return 5;
-        } else if (size <= 128 * std::pow(2, 6)) {
+        } else if (size <= BASE_BLOCK_SIZE * std::pow(2, 6)) {
             return 6;
-        } else if (size <= 128 * std::pow(2, 7)) {
+        } else if (size <= BASE_BLOCK_SIZE * std::pow(2, 7)) {
             return 7;
-        } else if (size <= 128 * std::pow(2, 8)) {
+        } else if (size <= BASE_BLOCK_SIZE * std::pow(2, 8)) {
             return 8;
-        } else if (size <= 128 * std::pow(2, 9)) {
+        } else if (size <= BASE_BLOCK_SIZE * std::pow(2, 9)) {
             return 9;
         } else {
             abort();