diff --git a/src/mempool.c b/src/mempool.c
index 0f5679b48..f5c3e3b4c 100644
--- a/src/mempool.c
+++ b/src/mempool.c
@@ -64,7 +64,7 @@ struct mempool {
 MRB_API mempool*
 mempool_open(void)
 {
-  mrb_mempool *pool = (mempool*)malloc(sizeof(struct mempool));
+  mempool *pool = (mempool*)malloc(sizeof(struct mempool));
 
   if (pool) {
     pool->pages = NULL;