diff --git a/build/makefile_sundials b/build/makefile_sundials
index 78d7a752dcc00b9f3f75fa7c988eab9dd1acb357..6775654841d65057b2cf63991686d772ec27102d 100644
--- a/build/makefile_sundials
+++ b/build/makefile_sundials
@@ -19,10 +19,10 @@ ACTORS_LIBRARIES = -L/usr/lib -L/usr/local/lib -L/Summa-Actors/bin -lcaf_core -l
 
 
 # Production runs
-FLAGS_NOAH = -g -O3 -ffree-form -ffree-line-length-none -fmax-errors=0 -fPIC -Wfatal-errors
-FLAGS_COMM = -g -O3 -ffree-line-length-none -fmax-errors=0 -fPIC -Wfatal-errors
-FLAGS_SUMMA = -g -O3 -ffree-line-length-none -fmax-errors=0 -fPIC -Wfatal-errors
-FLAGS_ACTORS = -g -O3 -Wfatal-errors -std=c++17
+FLAGS_NOAH = -g -O0 -ffree-form -ffree-line-length-none -fmax-errors=0 -fPIC -Wfatal-errors
+FLAGS_COMM = -g -O0 -ffree-line-length-none -fmax-errors=0 -fPIC -Wfatal-errors
+FLAGS_SUMMA = -g -O0 -ffree-line-length-none -fmax-errors=0 -fPIC -Wfatal-errors
+FLAGS_ACTORS = -g -O0 -Wfatal-errors -std=c++17
 
 # Debug runs
 # FLAGS_NOAH = -g -O0 -ffree-form -ffree-line-length-none -fmax-errors=0 -fbacktrace -Wno-unused -Wno-unused-dummy-argument -fPIC
diff --git a/build/source/engine/var_derive.f90 b/build/source/engine/var_derive.f90
index 8227b04073da654f35983f89f36a000801157f3b..0432a41cadbe4be71faeb68ac354ebc5a6ed7b36 100755
--- a/build/source/engine/var_derive.f90
+++ b/build/source/engine/var_derive.f90
@@ -433,16 +433,16 @@ contains
   case(timeDelay)
    ! initialize
    pSave   = 0._dp ! cumulative probability at the start of the step
-   aLambda = routingGammaShape / routingGammaScale
-   if(routingGammaShape <= 0._dp .or. aLambda < 0._dp)then
+   if(routingGammaShape <= 0._dp .or. routingGammaScale <= 0._dp)then
     message=trim(message)//'bad arguments for the Gamma distribution'
+    print*, message
     err=20; return
    end if
    ! loop through time steps and compute fraction of runoff in future steps
    do iFuture = 1,nTDH
     ! get weight for a given bin
     tFuture = real(iFuture, kind(dt))*dt                  ! future time (end of step)
-    cumProb = gammp(routingGammaShape,aLambda*tFuture)    ! cumulative probability at the end of the step
+    cumProb = gammp(routingGammaShape,tFuture/routingGammaScale)    ! cumulative probability at the end of the step
     fractionFuture(iFuture) = max(0._dp, cumProb - pSave) ! fraction of runoff in the current step
     pSave   = cumProb                                     ! save the cumulative probability for use in the next step
     !write(*,'(a,1x,i4,1x,3(f20.10,1x))') trim(message), iFuture, tFuture, cumProb, fractionFuture(iFuture)
diff --git a/utils/laugh_tests/celia1990/verification_data/runinfo.txt b/utils/laugh_tests/celia1990/verification_data/runinfo.txt
index 25d398f9cfc44609989125b16d3833c10831c27f..2e294c3db47c5c2e65b97fb0ec50b4f6c9bf0658 100644
--- a/utils/laugh_tests/celia1990/verification_data/runinfo.txt
+++ b/utils/laugh_tests/celia1990/verification_data/runinfo.txt
@@ -1 +1 @@
- Run start time on system:  ccyy=2022 - mm=09 - dd=08 - hh=15 - mi=40 - ss=22.423
+ Run start time on system:  ccyy=2022 - mm=09 - dd=08 - hh=18 - mi=34 - ss=44.626
diff --git a/utils/laugh_tests/celia1990/verification_data/summa_celia1990_G1-1_timestep.nc b/utils/laugh_tests/celia1990/verification_data/summa_celia1990_G1-1_timestep.nc
index 775bcee947397e9f804622cef9a0f27570626598..742b84efc69328d9c226ba6c56077dfc4f318d64 100644
Binary files a/utils/laugh_tests/celia1990/verification_data/summa_celia1990_G1-1_timestep.nc and b/utils/laugh_tests/celia1990/verification_data/summa_celia1990_G1-1_timestep.nc differ