diff --git a/src/SyntOn.py b/src/SyntOn.py
index 62ecdaf..b06aeae 100644
--- a/src/SyntOn.py
+++ b/src/SyntOn.py
@@ -259,9 +259,9 @@ def __init__(self, outDir, Synthons = None, reactionSMARTS = None, maxNumberOfRe
         self.results = set()
         self.allReconstructedMols = []
         self.__marksCombinations = {'C:10': ['N:20', 'O:20', 'C:20', 'c:20', 'n:20', 'S:20'],
-                                    'c:10': ['N:20', 'O:20', 'C:20', 'c:20', 'n:20', 'S:20'],
+                                    'c:10': ['N:20', 'O:20', 'C:20', 'c:20', 'n:20', 'S:20', 'c:21'],
                                     'c:20': ['N:11', 'C:10', 'c:10'], 'C:20': ['C:10', 'c:10'],
-                                    'c:21': ['N:20', 'O:20', 'n:20'], 'C:21': ['N:20', 'n:20'],
+                                    'c:21': ['N:20', 'O:20', 'n:20', 'c:10'], 'C:21': ['N:20', 'n:20'],
                                     'N:20': ['C:10', 'c:10', 'C:21', 'c:21', 'S:10'], 'N:11': ['c:20'],
                                     'n:20': ['C:10', 'c:10', 'C:21', 'c:21'], 'O:20': ['C:10', 'c:10', 'c:21'],
                                     'S:20': ['C:10', 'c:10'], 'S:10': ['N:20'], 'C:30': ['C:40', 'N:40'],