diff --git a/Makefile.mahone b/Makefile.mahone
index bb02cbcb8a7ce3ca6405fc0f40013bd1cac5e344..82760f4a73ae7cf60920d3a4da4cfd2a300003ea 100644
--- a/Makefile.mahone
+++ b/Makefile.mahone
@@ -5,9 +5,9 @@ F90    = mpif90
 F77    = mpif77
 CC     = mpicc
 # wsmp wants mpich, so we try this
-F90    = /usr/local/mpich.pgi.64/bin/mpif90
-F77    = /usr/local/mpich.pgi.64/bin/mpif77
-CC     = /usr/local/mpich.pgi.64/bin/mpicc
+# F90    = /usr/local/mpich.pgi.64/bin/mpif90
+# F77    = /usr/local/mpich.pgi.64/bin/mpif77
+# CC     = /usr/local/mpich.pgi.64/bin/mpicc
 
 # The Makefiles look at compile output with this
 PAGER=less
@@ -16,7 +16,7 @@ PAGER=less
 #
 WSMP_DIR   = /home/dguptill/software/wsmp/wsmp-Linux/lib/X86_64/PGI
 
-# for 64 bit compile..................................
+# Miscellaneous things
 #
 AR=ar
 OPTIONS=
@@ -25,11 +25,34 @@ WSMP_LIB=-L$(WSMP_DIR) -lpwsmp64
 
 # Define FORTRAN compiler flags.......................
 #
+# Initial guess at flags:
+# Using these, douar works much as it does on grace.
 FFLAGS=-fastsse -pc 64 -Kieee -tp amd64
+# These might be better
+FFLAGS=-gopt -O2 -fastsse -Kieee
+# Some debugging options; trying for a failure like on the p690
+# We get a consistent crash where make_cut calls itself.
+# "Error: floating point exception, integer divide by zero"
+FFLAGS=-gopt -O0 -Kieee -Ktrap=inv,divz,ovf -mcmodel=medium \
+-Mnofprelaxed -Mbounds -Mchkstk -Mnofpapprox \
+-Mchkptr -Mnoonetrip -Mrecursive
+# trying these; we get less information from the debugger.
+# FFLAGS=-O2 -fastsse -gopt -Kieee -Ktrap=inv,divz,ovf -mcmodel=medium -Mbounds
+
+#-traceback
 
 # Define C compiler flags.............................
 #
+# Initial guess at flags:
+# Using these, douar works much as it does on grace.
 CFLAGS=-fastsse -pc 64 -Kieee -tp amd64
+# These might be better
+CFLAGS=-fastsse -Kieee
+# Some debugging options; trying for a failure like on the p690
+CFLAGS=-gopt -O0 -Kieee -Ktrap=inv,divz,ovf -mcmodel=medium \
+-Mnofprelaxed -Mbounds -Mchkstk -Mnofpapprox \
+-Mzerotrip
+# CFLAGS=-O2 -fastsse -gopt -Kieee -Ktrap=inv,divz,ovf -mcmodel=medium -Mbounds
 
 # compile rules.......................................
 #
@@ -56,6 +79,7 @@ COMPILE_OUT=$(NAME).compile
 #
 
 LIBS = \
+ -lpthread -lacml \
  -LOCTREE -lOctree$(BITS) \
  -LNN -lnn_f$(BITS) \
  -LNN -lnn_c$(BITS) \
@@ -63,8 +87,5 @@ LIBS = \
  -LRESAMPLE -lresample$(BITS) \
  -L$(PGPLOT) -lpgplot \
  -L/usr/X11R6/lib64 -lX11 \
- $(WSMP_LIB) \
- -lacml -lpthread 
-
-
+ $(WSMP_LIB)