diff --git a/src/gc/alloc_resources.c b/src/gc/alloc_resources.c
index 2740f34..b7eaeda 100644
--- a/src/gc/alloc_resources.c
+++ b/src/gc/alloc_resources.c
@@ -454,19 +454,21 @@ compact_pool(PARROT_INTERP,
     if (mem_pools->gc_sweep_block_level)
         return;
 
+    ++mem_pools->gc_sweep_block_level;
+
+    /* We're collecting */
+    mem_pools->mem_allocs_since_last_collect    = 0;
+    mem_pools->header_allocs_since_last_collect = 0;
     ++mem_pools->gc_collect_runs;
 
     /* Snag a block big enough for everything */
     total_size = pad_pool_size(pool);
 
-    if (total_size == 0)
+    if (total_size == 0) {
+        free_old_mem_blocks(mem_pools, pool, pool->top_block, total_size);
+        --mem_pools->gc_sweep_block_level;
         return;
-
-    ++mem_pools->gc_sweep_block_level;
-
-    /* We're collecting */
-    mem_pools->mem_allocs_since_last_collect    = 0;
-    mem_pools->header_allocs_since_last_collect = 0;
+    }
 
     alloc_new_block(mem_pools, total_size, pool, "inside compact");