diff --git a/public/java/src/org/broadinstitute/sting/utils/variantcontext/VariantContextBuilder.java b/public/java/src/org/broadinstitute/sting/utils/variantcontext/VariantContextBuilder.java
index d8ab4bd23..40ac089ef 100644
--- a/public/java/src/org/broadinstitute/sting/utils/variantcontext/VariantContextBuilder.java
+++ b/public/java/src/org/broadinstitute/sting/utils/variantcontext/VariantContextBuilder.java
@@ -94,6 +94,7 @@ public class VariantContextBuilder {
         this.start = start;
         this.stop = stop;
         this.alleles = alleles;
+        this.attributes = Collections.emptyMap(); // immutable
         toValidate.add(VariantContext.Validation.ALLELES);
     }
 
diff --git a/public/java/test/org/broadinstitute/sting/utils/variantcontext/VariantContextUnitTest.java b/public/java/test/org/broadinstitute/sting/utils/variantcontext/VariantContextUnitTest.java
index 272166c68..19620b8df 100755
--- a/public/java/test/org/broadinstitute/sting/utils/variantcontext/VariantContextUnitTest.java
+++ b/public/java/test/org/broadinstitute/sting/utils/variantcontext/VariantContextUnitTest.java
@@ -750,6 +750,10 @@ public class VariantContextUnitTest extends BaseTest {
         modified = new VariantContextBuilder(modified).attributes(null).attribute("AC", 1).make();
         Assert.assertEquals(modified.getAttribute("AC"), 1);
 
+        // test the behavior when the builder's attribute object is not initialized
+        modified = new VariantContextBuilder(modified.getSource(), modified.getChr(), modified.getStart(), modified.getEnd(), modified.getAlleles()).attribute("AC", 1).make();
+
+        // test normal attribute modification
         modified = new VariantContextBuilder(cfg.vc).attribute("AC", 1).make();
         Assert.assertEquals(modified.getAttribute("AC"), 1);
         modified = new VariantContextBuilder(modified).attribute("AC", 2).make();