diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3813e10..8752bf9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 ### Changed
+- Modified default flags for NAG to allow more aggressive debug flags.  Mostly this is by using a more specific list of procedures for which interface "mismatch" warnings are suppressed.
 
 ## [3.32.0] - 2023-09-01
 
diff --git a/compiler/flags/NAG_Fortran.cmake b/compiler/flags/NAG_Fortran.cmake
index 8f1a8f4..af7790f 100644
--- a/compiler/flags/NAG_Fortran.cmake
+++ b/compiler/flags/NAG_Fortran.cmake
@@ -6,12 +6,13 @@ set (FREAL8 "-r8")
 set (FINT8 "-i8")
 set (PP    "-fpp")
 set (DUSTY "-dusty")
-set (MISMATCH "-mismatch_all")
+set (MISMATCH "-wmismatch=QSORTL,QSORTS,MPI_Recv,MPI_Send,MPI_Irecv,MPI_BCast,MPI_Allgather,MPI_Allgatherv,MPI_Allreduce,MPI_Scatterv,MPI_Gatherv,MPI_Sendrecv,MPI_File_write,MPI_File_read,MPI_File_Read_at_all,MPI_File_write_at_all,ESMF_UserCompSetInternalState,ESMF_UserCompGetInternalState")
 set (DISABLE_FIELD_WIDTH_WARNING)
 set (CRAY_POINTER "")
 set (EXTENDED_SOURCE "-132 -w=x95" )
 set (FIXED_SOURCE "-fixed")
-set (UNUSED_DUMMY "-w=uda")
+set (SUPPRESS_UNUSED_DUMMY "-w=uda")
+set (F2018 "-f2018")
 
 if (APPLE)
   option (ESMF_HAS_ACHAR_BUG "ESMF Compatibility issue" ON)
@@ -21,14 +22,13 @@ endif ()
 
 # Common Fortran Flags
 # --------------------
-set (common_Fortran_flags ${UNUSED_DUMMY})
+set (common_Fortran_flags "${F2018} ${MISMATCH}")
 set (common_Fortran_fpe_flags "") # "${DUSTY}")
 #set (common_Fortran_fpe_flags "")
 
 # GEOS Debug
 # ----------
-#set (GEOS_Fortran_Debug_Flags "-O0 -g")# -C=all") # -C=undefined")
-set (GEOS_Fortran_Debug_Flags "-O0 -g -C=all -Wp,-P")# -C=all ") # -C=undefined")
+set (GEOS_Fortran_Debug_Flags "-O0 -g -C=all") # -C=undefined")
 set (GEOS_Fortran_Debug_FPE_Flags "${common_Fortran_fpe_flags}")
 
 # GEOS Release