diff --git a/java/src/org/broadinstitute/sting/playground/gatk/walkers/AlleleFrequencyWalker.java b/java/src/org/broadinstitute/sting/playground/gatk/walkers/AlleleFrequencyWalker.java
index 5d9077fba..ba516585f 100755
--- a/java/src/org/broadinstitute/sting/playground/gatk/walkers/AlleleFrequencyWalker.java
+++ b/java/src/org/broadinstitute/sting/playground/gatk/walkers/AlleleFrequencyWalker.java
@@ -364,7 +364,8 @@ public class AlleleFrequencyWalker extends LocusWalker<AlleleFrequencyEstimate,
                                                                          depth,
                                                                          new String(bases),
                                                                          quals,
-                                                                         posteriors);
+                                                                         posteriors,
+																		 "unknown_sample");
         return alleleFreq;
     }