diff --git a/src/main/java/gov/usgs/earthquake/nshmp/gmm/MultiScalarGroundMotion.java b/src/main/java/gov/usgs/earthquake/nshmp/gmm/MultiScalarGroundMotion.java
index e11f512e3def09ed8a780ea3dadc73d543e078c6..b614551ee5ed6f0385f602a44fc82a4d90a4acca 100644
--- a/src/main/java/gov/usgs/earthquake/nshmp/gmm/MultiScalarGroundMotion.java
+++ b/src/main/java/gov/usgs/earthquake/nshmp/gmm/MultiScalarGroundMotion.java
@@ -1,6 +1,5 @@
 package gov.usgs.earthquake.nshmp.gmm;
 
-import gov.usgs.earthquake.nshmp.Maths;
 import gov.usgs.earthquake.nshmp.data.DoubleData;
 
 /**
@@ -37,7 +36,7 @@ public class MultiScalarGroundMotion extends DefaultScalarGroundMotion {
 
     super(
         DoubleData.weightedSumLn(means, meanWts),
-        Maths.srssWeighted(sigmas, sigmaWts));
+        DoubleData.weightedSum(sigmas, sigmaWts));
 
     this.means = means;
     this.meanWts = meanWts;