diff --git a/unix/ztypes_freebsd_arm64.go b/unix/ztypes_freebsd_arm64.go
index 1542a877..c681d7db 100644
--- a/unix/ztypes_freebsd_arm64.go
+++ b/unix/ztypes_freebsd_arm64.go
@@ -397,7 +397,7 @@ type Reg struct {
 }
 
 type FpReg struct {
-	Fp_q  [32]uint128
+	Fp_q  [512]uint8
 	Fp_sr uint32
 	Fp_cr uint32
 }