diff --git a/src/strainge/variant_caller.py b/src/strainge/variant_caller.py
index c15b712..fb2117c 100755
--- a/src/strainge/variant_caller.py
+++ b/src/strainge/variant_caller.py
@@ -604,7 +604,7 @@ def summarize(self):
         }
 
         summed_abun = sum(abun.values())
-        abun = {k: v / summed_abun for k, v in abun.items()}
+        abun = {k: v / summed_abun if summed_abun else 0 for k, v in abun.items()}
 
         # abundance of all references relative to whole metagenome
         total_aln_reads = self.passing_reads + self.lowmq_reads