diff --git a/cert_pruner/pruner.py b/cert_pruner/pruner.py
index d477bde..364e627 100644
--- a/cert_pruner/pruner.py
+++ b/cert_pruner/pruner.py
@@ -12,6 +12,7 @@ def __init__(self, days_old, profile=None):
         self._iam_client = self.session.client('iam')
         self._elb_client = self.session.client('elb')
         self._elbv2_client = self.session.client('elbv2')
+        self._cloudfront_client = self.session.client('cloudfront')
         self.days_old = days_old
 
     def _list_elb_certificates(self):
@@ -66,8 +67,10 @@ def _list_elbv2_certificates(self):
 
             # Loop through results and save all certificates attached to a listener
             for lb in lbs['LoadBalancers']:
-                for cert in self._get_elbv2_listener_certificates(lb['LoadBalancerArn']):
-                    certificates.add(cert)
+                # An error occurred (ValidationError) when calling the DescribeListenerCertificates operation: This operation does not support Network Load Balancer Listeners.
+                if 'network' != lb['Type']:
+                    for cert in self._get_elbv2_listener_certificates(lb['LoadBalancerArn']):
+                        certificates.add(cert)
 
             # Check for the next ALB marker
             if lbs.get('NextMarker'):
@@ -77,6 +80,41 @@ def _list_elbv2_certificates(self):
 
         return certificates
 
+    def _list_cloudfront_certIDs(self):
+        """
+        List all certificate IDs for IAM certs from all CloudFront distributions
+
+        :return: Set of IAM certificate IDs
+        :rtype: set of str
+        """
+        marker = None
+        certIDs = set()
+
+        while True:
+            # Fetch the data
+            if marker:
+                distributions = self._cloudfront_client.list_distributions(Marker=marker)
+            else:
+                distributions = self._cloudfront_client.list_distributions()
+
+            # Loop through results and save all certificates IDs listed for IAM
+            items = []
+            if 'DistributionList' in distributions and 'Items' in distributions['DistributionList']:
+                items = distributions['DistributionList']['Items']
+            for dist in items:
+                if 'ViewerCertificate' in dist:
+                    cert = dist['ViewerCertificate']
+                    if 'iam' == cert['CertificateSource']:
+                        certIDs.add( cert['IAMCertificateId'] )
+
+            # Check for the next ALB marker
+            if distributions.get('NextMarker'):
+                marker = distributions['NextMarker']
+            else:
+                break
+
+        return certIDs
+
     def _get_elbv2_listeners(self, arn):
         """
         Get all listener ARNs for a particular ELBv2 load balancer
@@ -185,6 +223,7 @@ def prune(self, delete=False):
 
         :param bool delete: Whether to perform a dry run or actually start the deletion
         """
+        deltaDaysOld = timedelta(days=self.days_old)
         attached_certs = set()
         prune_certs = []
 
@@ -196,10 +235,13 @@ def prune(self, delete=False):
         for cert in self._list_elbv2_certificates():
             attached_certs.add(cert)
 
+        # Find all attached certificates on CloudFront
+        distr_certs = self._list_cloudfront_certIDs()
+
         # Check each IAM certificate to see if it is in the attached certificates set
         print('Unattached Certificates:')
         for cert in self._list_iam_certificates():
-            if cert['Arn'] not in attached_certs:
+            if cert['Arn'] not in attached_certs and cert['ServerCertificateId'] not in distr_certs:
                 prune_certs.append(cert)
                 print('\tUNATTACHED: Expiring %s - %s' % (cert['Expiration'], cert['ServerCertificateName']))
 
@@ -212,13 +254,19 @@ def prune(self, delete=False):
 
             # Check if the certificate has already expired or if it was uploaded more than days_old days ago
             now = datetime.now(pytz.utc)
-            expired = cert['Expiration'] < now
-            if expired:
+            # I want to change the logic and not delete certs which might have expired, if we specify --days -90
+            #expired = cert['Expiration'] < now
+            if self.days_old < 0:
+                expired = now - cert['Expiration'] > abs(deltaDaysOld)
+                #print( 'DEBUG: deltaDaysOld =', deltaDaysOld, 'expired =', expired, "cert['Expiration'] =", cert['Expiration'], "now - cert['Expiration'] =", now - cert['Expiration'] )
+            else:
+                expired = cert['Expiration'] < now
+            if cert['Expiration'] < now:
                 expire_word = 'Expired '
             else:
                 expire_word = 'Expiring'
 
-            if expired or (self.days_old >= 0 and now - cert['UploadDate'] > timedelta(days=self.days_old)):
+            if expired or (self.days_old >= 0 and now - cert['UploadDate'] > deltaDaysOld ):
                 delete_certs.append({'cert': cert, 'expire_word': expire_word})
             else:
                 keep_certs.append({'cert': cert, 'expire_word': expire_word})
@@ -244,7 +292,7 @@ def prune(self, delete=False):
             if delete:
                 # Perform the deletion
                 self._iam_client.delete_server_certificate(
-                    ServerCertificateName=cert['ServerCertificateName']
+                    ServerCertificateName=cert['cert']['ServerCertificateName']
                 )
 
                 print('\tDELETED: Uploaded %s, %s %s - %s' % (