diff --git a/lib/ofp-actions.c b/lib/ofp-actions.c
index fe6a17b6dad..8a05f7c9c82 100644
--- a/lib/ofp-actions.c
+++ b/lib/ofp-actions.c
@@ -3402,21 +3402,21 @@ ofpact_put_set_field(struct ofpbuf *ofpacts, const struct mf_field *field,
     struct ofpact_set_field *sf = ofpact_put_SET_FIELD(ofpacts);
     sf->field = field;
 
-    /* Fill in the value and mask if given, otherwise put zeroes so that the
-     * caller may fill in the value and mask itself. */
+    /* Fill with all zeroes to make sure the padding is initialized. */
+    ofpbuf_put_zeros(ofpacts, total_size);
+    sf = ofpacts->header;
+
+    /* Fill in the value and mask if given, otherwise keep the zeroes
+     * so that the caller may fill in the value and mask itself. */
     if (value) {
-        ofpbuf_put_uninit(ofpacts, total_size);
-        sf = ofpacts->header;
         memcpy(sf->value, value, field->n_bytes);
         if (mask) {
             memcpy(ofpact_set_field_mask(sf), mask, field->n_bytes);
         } else {
             memset(ofpact_set_field_mask(sf), 0xff, field->n_bytes);
         }
-    } else {
-        ofpbuf_put_zeros(ofpacts, total_size);
-        sf = ofpacts->header;
     }
+
     /* Update length. */
     ofpact_finish_SET_FIELD(ofpacts, &sf);