diff --git a/PyKCS11/__init__.py b/PyKCS11/__init__.py
index aac7a8f..2d2615c 100644
--- a/PyKCS11/__init__.py
+++ b/PyKCS11/__init__.py
@@ -33,6 +33,7 @@
 CKC = {}
 CKF = {}
 CKG = {}
+CKH = {}
 CKK = {}
 CKM = {}
 CKO = {}
@@ -47,6 +48,7 @@
       or x[:4] == 'CKC_' \
       or x[:4] == 'CKF_' \
       or x[:4] == 'CKG_' \
+      or x[:4] == 'CKH_' \
       or x[:4] == 'CKK_' \
       or x[:4] == 'CKM_' \
       or x[:4] == 'CKO_' \