diff --git a/src/os/unix/ngx_process.h b/src/os/unix/ngx_process.h
index 1eb545b..5b56509 100644
--- a/src/os/unix/ngx_process.h
+++ b/src/os/unix/ngx_process.h
@@ -46,7 +46,7 @@
 ngx_pid_t ngx_spawn_process(ngx_cycle_t *cycle,
                             ngx_spawn_proc_pt proc, void *data,
                             char *name, ngx_int_t respawn);
-ngx_int_t ngx_exec(ngx_cycle_t *cycle, ngx_exec_ctx_t *ctx);
+ngx_pid_t ngx_exec(ngx_cycle_t *cycle, ngx_exec_ctx_t *ctx);
 void ngx_signal_processes(ngx_cycle_t *cycle, ngx_int_t signo);
 void ngx_respawn_processes(ngx_cycle_t *cycle);
 void ngx_process_get_status(void);