diff --git a/core/iwasm/libraries/thread-mgr/thread_manager.c b/core/iwasm/libraries/thread-mgr/thread_manager.c
index c00685607..f6987c0c8 100644
--- a/core/iwasm/libraries/thread-mgr/thread_manager.c
+++ b/core/iwasm/libraries/thread-mgr/thread_manager.c
@@ -344,13 +344,13 @@ wasm_cluster_spawn_exec_env(WASMExecEnv *exec_env)
 {
     WASMCluster *cluster = wasm_exec_env_get_cluster(exec_env);
     wasm_module_inst_t module_inst = get_module_inst(exec_env);
-    wasm_module_t module = wasm_exec_env_get_module(exec_env);
+    wasm_module_t module;
     wasm_module_inst_t new_module_inst;
     WASMExecEnv *new_exec_env;
     uint32 aux_stack_start, aux_stack_size;
     uint32 stack_size = 8192;
 
-    if (!module) {
+    if (!module_inst || !(module = wasm_exec_env_get_module(exec_env))) {
         return NULL;
     }
 
@@ -373,11 +373,9 @@ wasm_cluster_spawn_exec_env(WASMExecEnv *exec_env)
         return NULL;
     }
 
-    if (module_inst) {
-        /* Set custom_data to new module instance */
-        wasm_runtime_set_custom_data_internal(
-            new_module_inst, wasm_runtime_get_custom_data(module_inst));
-    }
+    /* Set custom_data to new module instance */
+    wasm_runtime_set_custom_data_internal(
+        new_module_inst, wasm_runtime_get_custom_data(module_inst));
 
     new_exec_env = wasm_exec_env_create_internal(new_module_inst,
                                                  exec_env->wasm_stack_size);
diff --git a/core/iwasm/libraries/thread-mgr/thread_manager.h b/core/iwasm/libraries/thread-mgr/thread_manager.h
index ca1cd8f80..e99efc99c 100644
--- a/core/iwasm/libraries/thread-mgr/thread_manager.h
+++ b/core/iwasm/libraries/thread-mgr/thread_manager.h
@@ -15,65 +15,9 @@
 #ifdef __cplusplus
 extern "C" {
 #endif
+
 #if WASM_ENABLE_DEBUG_INTERP != 0
-#define WAMR_SIG_TRAP (5)
-#define WAMR_SIG_STOP (19)
-#define WAMR_SIG_TERM (15)
-#define WAMR_SIG_SINGSTEP (0x1ff)
-
-#define STATUS_RUNNING (0)
-#define STATUS_STOP (1)
-#define STATUS_EXIT (2)
-#define STATUS_STEP (3)
-
-#define IS_WAMR_TERM_SIG(signo) ((signo) == WAMR_SIG_TERM)
-
-#define IS_WAMR_STOP_SIG(signo) \
-    ((signo) == WAMR_SIG_STOP || (signo) == WAMR_SIG_TRAP)
-
-typedef struct WASMCurrentEnvStatus {
-    uint64 signal_flag : 32;
-    uint64 step_count : 16;
-    uint64 running_status : 16;
-    korp_mutex wait_lock;
-    korp_cond wait_cond;
-} WASMCurrentEnvStatus;
-
 typedef struct WASMDebugInstance WASMDebugInstance;
-
-WASMCurrentEnvStatus *
-wasm_cluster_create_exenv_status();
-
-void
-wasm_cluster_destroy_exenv_status(WASMCurrentEnvStatus *status);
-
-void
-wasm_cluster_send_signal_all(WASMCluster *cluster, uint32 signo);
-
-void
-wasm_cluster_thread_stopped(WASMExecEnv *exec_env);
-
-void
-wasm_cluster_thread_waiting_run(WASMExecEnv *exec_env);
-
-void
-wasm_cluster_wait_thread_status(WASMExecEnv *exec_env, uint32 *status);
-
-void
-wasm_cluster_thread_exited(WASMExecEnv *exec_env);
-
-void
-wasm_cluster_thread_continue(WASMExecEnv *exec_env);
-
-void
-wasm_cluster_thread_send_signal(WASMExecEnv *exec_env, uint32 signo);
-
-void
-wasm_cluster_thread_step(WASMExecEnv *exec_env);
-
-void
-wasm_cluster_set_debug_inst(WASMCluster *cluster, WASMDebugInstance *inst);
-
 #endif
 typedef struct WASMCluster {
     struct WASMCluster *next;
@@ -183,6 +127,65 @@ void
 wasm_cluster_spread_custom_data(WASMModuleInstanceCommon *module_inst,
                                 void *custom_data);
 
+#if WASM_ENABLE_DEBUG_INTERP != 0
+#define WAMR_SIG_TRAP (5)
+#define WAMR_SIG_STOP (19)
+#define WAMR_SIG_TERM (15)
+#define WAMR_SIG_SINGSTEP (0x1ff)
+
+#define STATUS_RUNNING (0)
+#define STATUS_STOP (1)
+#define STATUS_EXIT (2)
+#define STATUS_STEP (3)
+
+#define IS_WAMR_TERM_SIG(signo) ((signo) == WAMR_SIG_TERM)
+
+#define IS_WAMR_STOP_SIG(signo) \
+    ((signo) == WAMR_SIG_STOP || (signo) == WAMR_SIG_TRAP)
+
+typedef struct WASMCurrentEnvStatus {
+    uint64 signal_flag : 32;
+    uint64 step_count : 16;
+    uint64 running_status : 16;
+    korp_mutex wait_lock;
+    korp_cond wait_cond;
+} WASMCurrentEnvStatus;
+
+WASMCurrentEnvStatus *
+wasm_cluster_create_exenv_status();
+
+void
+wasm_cluster_destroy_exenv_status(WASMCurrentEnvStatus *status);
+
+void
+wasm_cluster_send_signal_all(WASMCluster *cluster, uint32 signo);
+
+void
+wasm_cluster_thread_stopped(WASMExecEnv *exec_env);
+
+void
+wasm_cluster_thread_waiting_run(WASMExecEnv *exec_env);
+
+void
+wasm_cluster_wait_thread_status(WASMExecEnv *exec_env, uint32 *status);
+
+void
+wasm_cluster_thread_exited(WASMExecEnv *exec_env);
+
+void
+wasm_cluster_thread_continue(WASMExecEnv *exec_env);
+
+void
+wasm_cluster_thread_send_signal(WASMExecEnv *exec_env, uint32 signo);
+
+void
+wasm_cluster_thread_step(WASMExecEnv *exec_env);
+
+void
+wasm_cluster_set_debug_inst(WASMCluster *cluster, WASMDebugInstance *inst);
+
+#endif /* end of WASM_ENABLE_DEBUG_INTERP != 0 */
+
 #ifdef __cplusplus
 }
 #endif