diff --git a/Build/makefile b/Build/makefile
index 483d9fc11cf..557168a48aa 100644
--- a/Build/makefile
+++ b/Build/makefile
@@ -343,7 +343,7 @@ ompi_intel_linux : setup $(obj_mpi)
 
 #*** GNU Compilers ***
 
-ompi_gnu_linux : FFLAGS = -m64 -O2 -std=f2018 -frecursive -ffpe-summary=none -fall-intrinsics $(GITINFOGNU) $(FFLAGSMKL_GNU_OPENMPI) $(GFORTRAN_OPTIONS) $(FFLAGS_HYPRE) $(FFLAGS_SUNDIALS)
+ompi_gnu_linux : FFLAGS = -m64 -O3 -std=f2018 -frecursive -ffpe-summary=none -fall-intrinsics $(GITINFOGNU) $(FFLAGSMKL_GNU_OPENMPI) $(GFORTRAN_OPTIONS) $(FFLAGS_HYPRE) $(FFLAGS_SUNDIALS)
 ompi_gnu_linux : LFLAGSMKL = $(LFLAGSMKL_GNU_OPENMPI) $(LFLAGS_HYPRE) $(LFLAGS_SUNDIALS)
 ompi_gnu_linux : FCOMPL = $(COMP_FC)
 ompi_gnu_linux : FOPENMPFLAGS = -fopenmp
diff --git a/Source/wall.f90 b/Source/wall.f90
index 91355aa347b..bf10653df35 100644
--- a/Source/wall.f90
+++ b/Source/wall.f90
@@ -2888,7 +2888,7 @@ SUBROUTINE PERFORM_PYROLYSIS
 REAL(EB), DIMENSION(MAX_LPC) :: Q_DOT_PART,M_DOT_PART
 INTEGER :: ITER,MAX_ITER
 LOGICAL :: REMOVE_LAYER
-REAL(EB), PARAMETER :: M_DOT_ERROR_TOL=1.E-6_EB, CHAR_DENSITY_THRESHOLD=5.7_EB ! approx. ASH_DENSITY
+REAL(EB), PARAMETER :: M_DOT_ERROR_TOL=1.E-6_EB, CHAR_DENSITY_THRESHOLD=5._EB ! approx. ASH_DENSITY
 
 ! Get surface oxygen mass fraction