diff --git a/dm-compress/dm-compress.c b/dm-compress/dm-compress.c
index a9463d0..a50626f 100644
--- a/dm-compress/dm-compress.c
+++ b/dm-compress/dm-compress.c
@@ -504,6 +504,25 @@ lblk_alloc_elem_read(struct dm_compress* dc, struct zone_cache* zc, u64 lblk)
  * Logical block functions
  **************************************/
 
+static inline bool
+lblk_is_zeros(struct cbd_params* params, struct zone_cache* zc)
+{
+#ifdef CBD_DETECT_ZERO_BLOCKS
+    u32 off;
+    u32 len = PBLK_SIZE * lblk_per_pblk(params);
+
+    for (off = 0; off < len; ++off) {
+        if (zc->lblk[off]) {
+            return false;
+        }
+    }
+
+    return true;
+#else
+    return false;
+#endif
+}
+
 /*
  * Compress dc->lblk into dc->lz4_cbuf
  *
@@ -569,11 +588,7 @@ lblk_write(struct dm_compress* dc, struct zone_cache* zc)
     BUG_ON(zc->lblk_alloc_elem_lblk == LBLK_NONE);
 
     d_len = PBLK_SIZE * lblk_per_pblk(&dc->params);
-#ifdef CBD_DETECT_ZERO_BLOCKS
-    if (memcmpz(zc->lblk, d_len) == 0) {
-#else
-    if (0) {
-#endif
+    if (lblk_is_zeros(&dc->params, zc)) {
         c_len = 0;
         c_buf = NULL;
         zc->lblk_alloc_elem->len = 0;