diff --git a/sys/arm/arm/genassym.c b/sys/arm/arm/genassym.c
index de0ce7297320..5583cabedf8d 100644
--- a/sys/arm/arm/genassym.c
+++ b/sys/arm/arm/genassym.c
@@ -92,6 +92,7 @@ ASSYM(TD_FLAGS, offsetof(struct thread, td_flags));
 ASSYM(TD_PROC, offsetof(struct thread, td_proc));
 ASSYM(TD_FRAME, offsetof(struct thread, td_frame));
 ASSYM(TD_MD, offsetof(struct thread, td_md));
+ASSYM(TD_LOCK, offsetof(struct thread, td_lock));
 ASSYM(MD_TP, offsetof(struct mdthread, md_tp));
 
 ASSYM(TF_R0, offsetof(struct trapframe, tf_r0));