diff --git a/src/connection_pool.c b/src/connection_pool.c
index 9e6498d..9490dd5 100644
--- a/src/connection_pool.c
+++ b/src/connection_pool.c
@@ -52,7 +52,11 @@ static int node_init_for_rdma(ConnectionNode *node,
 static inline void conn_pool_get_key(const ConnectionInfo *conn,
         char *key, int *key_len)
 {
-    *key_len = sprintf(key, "%s-%u", conn->ip_addr, conn->port);
+    *key_len = strlen(conn->ip_addr);
+    memcpy(key, conn->ip_addr, *key_len);
+    *(key + (*key_len)++) = '-';
+    *(key + (*key_len)++) = (conn->port >> 8) & 0xFF;
+    *(key + (*key_len)++) = conn->port & 0xFF;
 }
 
 static int close_conn(ConnectionPool *cp, ConnectionManager *cm,
diff --git a/src/tests/Makefile b/src/tests/Makefile
index 3a7bd09..7aa22a8 100644
--- a/src/tests/Makefile
+++ b/src/tests/Makefile
@@ -11,7 +11,7 @@ ALL_PRGS = test_allocator test_skiplist test_multi_skiplist test_mblock test_blo
            test_server_id_func test_pipe test_atomic test_file_write_hole test_file_lock \
            test_pthread_wait test_thread_pool test_data_visible test_mutex_lock_perf \
            test_queue_perf test_normalize_path test_sorted_array test_sorted_queue   \
-           test_thread_local test_memcpy mblock_benchmark
+           test_thread_local test_memcpy mblock_benchmark cpool_benchmark
 
 all: $(ALL_PRGS)
 
diff --git a/src/tests/cpool_benchmark.c b/src/tests/cpool_benchmark.c
index 2a5b6fd..b2c49d7 100644
--- a/src/tests/cpool_benchmark.c
+++ b/src/tests/cpool_benchmark.c
@@ -28,7 +28,7 @@
 #include "fastcommon/connection_pool.h"
 
 static int thread_count = 2;
-static int64_t loop_count = 1000000;
+static int64_t loop_count = 10000000;
 static ConnectionPool cpool;
 
 static void *thread_run(void *args)