diff --git a/tests/test_survival_biasing/materials.xml b/tests/test_survival_biasing/materials.xml
index 1f85510e0d..1382ad5952 100644
--- a/tests/test_survival_biasing/materials.xml
+++ b/tests/test_survival_biasing/materials.xml
@@ -2,8 +2,9 @@
 <materials>
 
   <material id="1">
-    <density value="4.5" units="g/cc" />
-    <nuclide name="U-235" xs="70c" ao="1.0" />
+    <density value="19.5" units="g/cc" />
+    <nuclide name="U-235" xs="70c" ao="2.0" />
+    <nuclide name="U-238" xs="70c" ao="1.0" />
   </material>
 
 </materials>
diff --git a/tests/test_survival_biasing/results_true.dat b/tests/test_survival_biasing/results_true.dat
index 27f6ffb6d9..f733b4050d 100644
--- a/tests/test_survival_biasing/results_true.dat
+++ b/tests/test_survival_biasing/results_true.dat
@@ -1,2 +1,2 @@
 k-combined:
-0.30487324 0.00983400
+0.96880768 0.06981246