diff --git a/src/constants.F90 b/src/constants.F90
index 1ca896c3f9..375c517e76 100644
--- a/src/constants.F90
+++ b/src/constants.F90
@@ -66,7 +66,7 @@ module constants
        MASS_NEUTRON_MEV = 939.565379_8,      & ! mass of a neutron in MeV/c^2
        MASS_PROTON      = 1.007276466812_8,  & ! mass of a proton in amu
        AMU              = 1.660538921e-27_8, & ! 1 amu in kg
-       C_LIGHT          = 2.99792458e10_8,   & ! speed of light in cm/s
+       C_LIGHT          = 2.99792458e8_8,    & ! speed of light in m/s
        N_AVOGADRO       = 0.602214129_8,     & ! Avogadro's number in 10^24/mol
        K_BOLTZMANN      = 8.6173324e-11_8,   & ! Boltzmann constant in MeV/K
        INFINITY         = huge(0.0_8),       & ! positive infinity
diff --git a/src/tally.F90 b/src/tally.F90
index 31bce232a0..a5d7f3f0de 100644
--- a/src/tally.F90
+++ b/src/tally.F90
@@ -148,12 +148,16 @@ contains
           else
             score = p % last_wgt
           end if
+
+          ! Score the flux weighted inverse velocity with velocity in units of
+          ! cm/s
           score = score / material_xs % total &
-               / (sqrt(TWO * E / (MASS_NEUTRON_MEV)) * C_LIGHT)
+               / (sqrt(TWO * E / (MASS_NEUTRON_MEV)) * C_LIGHT * 100.0)
 
         else
-          ! For inverse velocity, we don't need a cross section
-          score = flux / (sqrt(TWO * E / (MASS_NEUTRON_MEV)) * C_LIGHT)
+          ! For inverse velocity, we don't need a cross section. The velocity is
+          ! in units of cm/s.
+          score = flux / (sqrt(TWO * E / (MASS_NEUTRON_MEV)) * C_LIGHT * 100.0)
         end if