diff --git a/lib/bcheck.c b/lib/bcheck.c
index 272b8070..c2ca3768 100644
--- a/lib/bcheck.c
+++ b/lib/bcheck.c
@@ -65,6 +65,7 @@
  || defined(__NetBSD__) \
  || defined(__dietlibc__)
 
+#include <sys/mman.h>
 #define INIT_SEM()
 #define EXIT_SEM()
 #define WAIT_SEM()
@@ -220,8 +221,8 @@ typedef struct alloca_list_struct {
 #define BOUND_TID_TYPE   DWORD
 #define BOUND_GET_TID    GetCurrentThreadId()
 #elif defined(__OpenBSD__)
-#define BOUND_TID_TYPE   int
-#define BOUND_GET_TID    0
+#define BOUND_TID_TYPE   pid_t
+#define BOUND_GET_TID    syscall (SYS_getthrid)
 #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) || defined(__riscv)
 #define BOUND_TID_TYPE   pid_t
 #define BOUND_GET_TID    syscall (SYS_gettid)