diff --git a/README.md b/README.md
index ac3a5bb..61b1ca1 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ Requirements
 ------------
 
   * Python (2.7+ and 3.5+ should work)
-  * cryptography>=0.6 (usually includes the optional idna module)
+  * cryptography>=2.1 (older versions break idna handling)
 
 Optional requirements (to use specified features)
 ------------------------------------------------------
@@ -121,4 +121,4 @@ Please keep the following in mind when using this software:
      * Create a dedicated user for acertmgr (e.g. acertmgr)
      * Run a acertmgr as that user (add acertmgr to that users cron!)
      * Access rights to read/write all files configured with the created user
-     * Run any programs/scripts defined on cert update as the created user (might need work-arounds with sudo or wrapper scripts)
\ No newline at end of file
+     * Run any programs/scripts defined on cert update as the created user (might need work-arounds with sudo or wrapper scripts)
diff --git a/acertmgr/tools.py b/acertmgr/tools.py
index 356551b..213a893 100644
--- a/acertmgr/tools.py
+++ b/acertmgr/tools.py
@@ -243,8 +243,7 @@ def get_cert_domains(cert):
     if san_cert:
         for d in san_cert.value:
             domains.add(d.value)
-    # Convert IDNA domain to correct representation and return the list
-    return [x for x, _ in idna_convert(domains)]
+    return domains
 
 
 # @brief determine certificate cn