diff --git a/src/cmfd_data.F90 b/src/cmfd_data.F90
index 64a069846..a26c60702 100644
--- a/src/cmfd_data.F90
+++ b/src/cmfd_data.F90
@@ -266,7 +266,7 @@ contains
     end do TAL
 
     ! normalize openmc source distribution
-    cmfd % openmc_src = cmfd % openmc_src/sum(cmfd % openmc_src)
+    cmfd % openmc_src = cmfd % openmc_src/sum(cmfd % openmc_src)*cmfd%norm
 
   end subroutine compute_xs
 
diff --git a/src/cmfd_execute.F90 b/src/cmfd_execute.F90
index baef72422..2d8fe1788 100644
--- a/src/cmfd_execute.F90
+++ b/src/cmfd_execute.F90
@@ -191,6 +191,7 @@ contains
     integer :: idx ! index in vector
     real(8) :: hxyz(3) ! cell dimensions of current ijk cell
     real(8) :: vol     ! volume of cell
+    real(8) :: norm    ! normalization factor for entropy
     real(8),allocatable :: source(:,:,:,:)  ! tmp source array for entropy
 
     ! get maximum of spatial and group indices
@@ -235,12 +236,15 @@ contains
 
     end do ZLOOP
 
-    ! normalize source such that it sums to 1.0
-    cmfd%source = cmfd%source/sum(cmfd%source)
+    ! normalize source such that it sums to 1.0 (1 group for now)
+    cmfd%source = cmfd%source/sum(cmfd%source)*cmfd%norm
 
     ! compute entropy
     if (entropy_on) then
 
+      ! compute normalization factor
+      norm = sum(cmfd%source)
+
       ! allocate tmp array
       if (.not.allocated(source)) allocate(source(ng,nx,ny,nz))
 
@@ -249,7 +253,7 @@ contains
 
       ! compute log
       where (cmfd%source > 0.0_8)
-        source = cmfd%source*log(cmfd%source)/log(2.0)
+        source = cmfd%source/norm*log(cmfd%source/norm)/log(2.0)
       end where
 
       ! sum that source
diff --git a/src/cmfd_header.F90 b/src/cmfd_header.F90
index e25c358be..f84402ea8 100644
--- a/src/cmfd_header.F90
+++ b/src/cmfd_header.F90
@@ -66,6 +66,9 @@ module cmfd_header
     ! openmc source
     real(8), allocatable  :: openmc_src(:,:,:,:)
 
+    ! openmc source normalization factor
+    real(8) :: norm = 1.0_8
+
   end type cmfd_obj
 
 contains
diff --git a/src/cmfd_input.F90 b/src/cmfd_input.F90
index 1836c1f25..fea1d532e 100644
--- a/src/cmfd_input.F90
+++ b/src/cmfd_input.F90
@@ -69,9 +69,13 @@ contains
    end if
 
     ! check for core map activation by printing note
-
     if (cmfd_coremap .and. master) write(*,*)"Core Map Overlay Activated"
 
+    ! check for normalization constant
+    if (norm_ > 0.0_8) then
+      cmfd % norm = norm_
+    end if
+
     ! create tally objects
     call create_cmfd_tally()
 
diff --git a/src/xml-fortran/templates/cmfd_t.xml b/src/xml-fortran/templates/cmfd_t.xml
index 00aadc3ee..cbba27bd0 100644
--- a/src/xml-fortran/templates/cmfd_t.xml
+++ b/src/xml-fortran/templates/cmfd_t.xml
@@ -13,5 +13,6 @@
   </typedef>
 
   <variable name="mesh_" tag="mesh" type="mesh_xml" />
+  <variable name="norm_" tag="norm" type="double" />
 
 </template>