diff --git a/analysis/frag_utils.py b/analysis/frag_utils.py
index e62128e..f6fc669 100644
--- a/analysis/frag_utils.py
+++ b/analysis/frag_utils.py
@@ -354,7 +354,8 @@ def compute_distance_and_angle(mol, smi_linker, smi_frags):
         frags_matches = list(mol.GetSubstructMatches(qfrag, uniquify=False))
         qlinker = Chem.AdjustQueryProperties(linker,qp)
         linker_matches = list(mol.GetSubstructMatches(qlinker, uniquify=False))
-            
+        if len(linker_matches) == 0:
+            linker_matches = [()]
         # Loop over matches
         for frag_match, linker_match in product(frags_matches, linker_matches):
             # Check if match
diff --git a/data/frag_utils.py b/data/frag_utils.py
index c3578d6..0722d06 100644
--- a/data/frag_utils.py
+++ b/data/frag_utils.py
@@ -352,7 +352,8 @@ def compute_distance_and_angle(mol, smi_linker, smi_frags):
         frags_matches = list(mol.GetSubstructMatches(qfrag, uniquify=False))
         qlinker = Chem.AdjustQueryProperties(linker,qp)
         linker_matches = list(mol.GetSubstructMatches(qlinker, uniquify=False))
-            
+        if len(linker_matches) == 0:
+            linker_matches = [()]
         # Loop over matches
         for frag_match, linker_match in product(frags_matches, linker_matches):
             # Check if match