diff --git a/CHANGELOG.md b/CHANGELOG.md
index 389bdb1..680aa3a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+- Update Intel LLVM Fortran flags to use `-march=x86-64-v3` as `-march=core-avx2` is not (technically?) supported by `ifx`
 - Change f2py detection for the odd case where there might be multiple Python installations. For now, if the path to the Python executable does not match the path to the f2py executable, we issue a `WARNING`. We use a `WARNING` since some installations (e.g., Spack) will have the Python executable in a different location than the f2py executable.
 - Removed warning that Baselibs is not supported, to a STATUS message.
 
diff --git a/compiler/flags/IntelLLVM_Fortran.cmake b/compiler/flags/IntelLLVM_Fortran.cmake
index 6549292..29a5cc3 100644
--- a/compiler/flags/IntelLLVM_Fortran.cmake
+++ b/compiler/flags/IntelLLVM_Fortran.cmake
@@ -63,23 +63,18 @@ set (NO_RANGE_CHECK "")
 
 cmake_host_system_information(RESULT proc_description QUERY PROCESSOR_DESCRIPTION)
 if (${proc_description} MATCHES "EPYC")
-  # AMD EPYC processors support AVX2, but only via the -march=core-avx2 flag
-  set (COREAVX2_FLAG "-march=core-avx2")
+  set (MARCH_FLAG "-march=x86-64-v3")
 elseif (${proc_description} MATCHES "Hygon")
-  # Hygon processors support AVX2, but only via the -march=core-avx2 flag
-  set (COREAVX2_FLAG "-march=core-avx2")
+  set (MARCH_FLAG "-march=x86-64-v3")
 elseif (${proc_description} MATCHES "Intel")
   # All the Intel processors that GEOS runs on support AVX2, but to be
-  # consistent with the AMD processors, we use the -march=core-avx2 flag
-  set (COREAVX2_FLAG "-march=core-avx2")
-  # Previous versions of GEOS used this flag, which was not portable
-  # for AMD. Keeping here for a few versions for historical purposes.
-  #set (COREAVX2_FLAG "-xCORE-AVX2")
+  # consistent with the AMD processors, we use the -march=x86-64-v3 flag
+  set (MARCH_FLAG "-march=x86-64-v3")
 elseif ( ${CMAKE_HOST_SYSTEM_PROCESSOR} STREQUAL "x86_64" )
   # This is a fallback for when the above doesn't work. It should work
   # for most x86_64 processors, but it is not guaranteed to be optimal.
   message(WARNING "Unknown processory type. Defaulting to a generic x86_64 processor. Performance may be suboptimal.")
-  set (COREAVX2_FLAG "")
+  set (MARCH_FLAG "x86-64")
 else ()
   message(FATAL_ERROR "Unknown processor. Please file an issue at https://github.com/GEOS-ESM/ESMA_cmake")
 endif ()
@@ -108,7 +103,7 @@ set (GEOS_Fortran_NoVect_FPE_Flags "${common_Fortran_fpe_flags} ${ARCH_CONSISTEN
 
 # GEOS Vectorize
 # --------------
-set (GEOS_Fortran_Vect_Flags "${FOPT3} ${DEBINFO} ${COREAVX2_FLAG} -fma -qopt-report0 ${FTZ} ${ALIGN_ALL} ${NO_ALIAS} -align array32byte")
+set (GEOS_Fortran_Vect_Flags "${FOPT3} ${DEBINFO} ${MARCH_FLAG} -fma -qopt-report0 ${FTZ} ${ALIGN_ALL} ${NO_ALIAS} -align array32byte")
 set (GEOS_Fortran_Vect_FPE_Flags "${FPE3} ${FP_MODEL_CONSISTENT} ${NOOLD_MAXMINLOC}")
 
 # GEOS Release
@@ -118,7 +113,7 @@ set (GEOS_Fortran_Release_FPE_Flags "${GEOS_Fortran_Vect_FPE_Flags}")
 
 # GEOS Aggressive
 # ---------------
-set (GEOS_Fortran_Aggressive_Flags "${FOPT3} ${DEBINFO} ${COREAVX2_FLAG} -fma -qopt-report0 ${FTZ} ${ALIGN_ALL} ${NO_ALIAS} -align array32byte")
+set (GEOS_Fortran_Aggressive_Flags "${FOPT3} ${DEBINFO} ${MARCH_FLAG} -fma -qopt-report0 ${FTZ} ${ALIGN_ALL} ${NO_ALIAS} -align array32byte")
 #set (GEOS_Fortran_Aggressive_Flags "${FOPT3} ${DEBINFO} -xSKYLAKE-AVX512 -qopt-zmm-usage=high -fma -qopt-report0 ${FTZ} ${ALIGN_ALL} ${NO_ALIAS} -align array64byte")
 set (GEOS_Fortran_Aggressive_FPE_Flags "${FPE3} ${FP_MODEL_FAST2} ${USE_SVML} ${NOOLD_MAXMINLOC}")