diff --git a/module/zfs/ddt_zap.c b/module/zfs/ddt_zap.c
index d6a991c7c1..280bff35a0 100644
--- a/module/zfs/ddt_zap.c
+++ b/module/zfs/ddt_zap.c
@@ -58,14 +58,16 @@ ddt_zap_destroy(objset_t *os, uint64_t object, dmu_tx_t *tx)
 static int
 ddt_zap_lookup(objset_t *os, uint64_t object, ddt_entry_t *dde)
 {
-	uchar_t cbuf[sizeof (dde->dde_phys) + 1];
+	uchar_t *cbuf;
 	uint64_t one, csize;
 	int error;
 
+	cbuf = kmem_alloc(sizeof (dde->dde_phys) + 1, KM_SLEEP);
+
 	error = zap_length_uint64(os, object, (uint64_t *)&dde->dde_key,
 	    DDT_KEY_WORDS, &one, &csize);
 	if (error)
-		return (error);
+		goto out;
 
 	ASSERT(one == 1);
 	ASSERT(csize <= sizeof (cbuf));
@@ -73,11 +75,13 @@ ddt_zap_lookup(objset_t *os, uint64_t object, ddt_entry_t *dde)
 	error = zap_lookup_uint64(os, object, (uint64_t *)&dde->dde_key,
 	    DDT_KEY_WORDS, 1, csize, cbuf);
 	if (error)
-		return (error);
+		goto out;
 
 	ddt_decompress(cbuf, dde->dde_phys, csize, sizeof (dde->dde_phys));
+out:
+	kmem_free(cbuf, sizeof (dde->dde_phys) + 1);
 
-	return (0);
+	return (error);
 }
 
 static void