diff --git a/src/gen_bpf.c b/src/gen_bpf.c
index 6961d09f..3787b7b0 100644
--- a/src/gen_bpf.c
+++ b/src/gen_bpf.c
@@ -364,6 +364,7 @@ static struct bpf_blk *_blk_resize(struct bpf_state *state,
 		_blk_free(state, blk);
 		return NULL;
 	}
+	memset(&new[blk->blk_cnt], 0, (blk->blk_alloc - blk->blk_cnt) * sizeof(*new));
 	blk->blks = new;
 
 	return blk;
@@ -452,6 +453,7 @@ static int _bpf_append_blk(struct bpf_program *prg, const struct bpf_blk *blk)
 		goto bpf_append_blk_failure;
 	}
 	prg->blks = i_new;
+	memset(&i_new[prg->blk_cnt - blk->blk_cnt], 0, blk->blk_cnt * sizeof(*(i_new)));
 
 	/* transfer and translate the blocks to raw instructions */
 	for (iter = 0; iter < blk->blk_cnt; iter++) {