--- a/src/per_field/f_field.tmpl.h
+++ b/src/per_field/f_field.tmpl.h
@@ -67,7 +67,7 @@
 mask_t gf_eq (const gf x, const gf y);
 mask_t gf_lobit (const gf x);
 
-void gf_serialize (uint8_t *serial, const gf x);
+void gf_serialize (uint8_t serial[SER_BYTES], const gf x);
 mask_t gf_deserialize (gf x, const uint8_t serial[SER_BYTES],uint8_t hi_nmask);