diff --git a/protected/java/src/org/broadinstitute/sting/gatk/walkers/compression/reducereads/BaseCounts.java b/protected/java/src/org/broadinstitute/sting/gatk/walkers/compression/reducereads/BaseCounts.java
index 3a3905710..778b8300a 100644
--- a/protected/java/src/org/broadinstitute/sting/gatk/walkers/compression/reducereads/BaseCounts.java
+++ b/protected/java/src/org/broadinstitute/sting/gatk/walkers/compression/reducereads/BaseCounts.java
@@ -227,7 +227,7 @@ import com.google.java.contract.Requires;
      * @param base      base
      * @return the proportion of this base over all other bases except indels
      */
-    @Requires("index.isNucleotide()")
+    @Requires("base.isNucleotide()")
     @Ensures({"result >=0.0", "result<= 1.0"})
     public double baseCountProportionWithoutIndels(final BaseIndex base) {
         final int total = totalCountWithoutIndels();