diff --git a/java/src/org/broadinstitute/sting/utils/genotype/calls/SSGGenotypeCall.java b/java/src/org/broadinstitute/sting/utils/genotype/calls/SSGGenotypeCall.java
index 2ea144f13..0760868cc 100644
--- a/java/src/org/broadinstitute/sting/utils/genotype/calls/SSGGenotypeCall.java
+++ b/java/src/org/broadinstitute/sting/utils/genotype/calls/SSGGenotypeCall.java
@@ -107,6 +107,8 @@ public class SSGGenotypeCall implements GenotypeCall, GenotypeOutput {
         for (SAMRecord r : pileup.getReads()) {
             rms += r.getMappingQuality() * r.getMappingQuality();
         }
+        rms /= pileup.getReads().size();
+        rms = Math.sqrt(rms);
         return rms;
     }