diff --git a/java/src/org/broadinstitute/sting/gatk/walkers/annotator/AlleleBalance.java b/java/src/org/broadinstitute/sting/gatk/walkers/annotator/AlleleBalance.java
index 15278bef8..b87243547 100755
--- a/java/src/org/broadinstitute/sting/gatk/walkers/annotator/AlleleBalance.java
+++ b/java/src/org/broadinstitute/sting/gatk/walkers/annotator/AlleleBalance.java
@@ -93,6 +93,10 @@ public class AlleleBalance implements VariantAnnotation {
             int refCount = counts[BaseUtils.simpleBaseToBaseIndex(ref)];
             int altCount = counts[BaseUtils.simpleBaseToBaseIndex(altBase)];
 
+            // sanity check
+            if ( refCount + altCount == 0 )
+                continue;
+
             double[] posteriors = ((PosteriorsBacked)g).getPosteriors();
             posteriors = MathUtils.normalizeFromLog10(posteriors);
             weights.add(posteriors[bestGenotype.ordinal()]);
diff --git a/java/src/org/broadinstitute/sting/gatk/walkers/annotator/OnOffGenotype.java b/java/src/org/broadinstitute/sting/gatk/walkers/annotator/OnOffGenotype.java
index 17b945dba..32d319dd6 100755
--- a/java/src/org/broadinstitute/sting/gatk/walkers/annotator/OnOffGenotype.java
+++ b/java/src/org/broadinstitute/sting/gatk/walkers/annotator/OnOffGenotype.java
@@ -97,6 +97,10 @@ public class OnOffGenotype implements VariantAnnotation {
             for (int i = 0; i < counts.length; i++)
                 totalCount += counts[i];
 
+            // sanity check
+            if ( totalCount == 0 )
+                continue;
+
             double[] posteriors = ((PosteriorsBacked)g).getPosteriors();
             posteriors = MathUtils.normalizeFromLog10(posteriors);
             weights.add(posteriors[bestGenotype.ordinal()]);