diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
index 6d1792cce56..42c001a7cda 100644
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
@@ -1485,6 +1485,13 @@ arc_hdr_realloc(arc_buf_hdr_t *hdr, kmem_cache_t *old, kmem_cache_t *new)
 		VERIFY(!HDR_L2_WRITING(hdr));
 		VERIFY3P(hdr->b_l1hdr.b_tmp_cdata, ==, NULL);
 
+#ifdef ZFS_DEBUG
+		if (hdr->b_l1hdr.b_thawed != NULL) {
+			kmem_free(hdr->b_l1hdr.b_thawed, 1);
+			hdr->b_l1hdr.b_thawed = NULL;
+		}
+#endif
+
 		nhdr->b_flags &= ~ARC_FLAG_HAS_L1HDR;
 	}
 	/*