diff --git a/CHANGELOG.md b/CHANGELOG.md
index 59bd867..a7566e3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased] - TBD
+### Added
+- Added definition of 0.125x0.15625 grid resolution
+
 ## [3.9.1] - 2024-06-28
 ### Fixed
 - Fixed formatting error in `.github/workflows/stale.yml` that caused the Mark Stale Issues action not to run
diff --git a/src/Core/hco_config_mod.F90 b/src/Core/hco_config_mod.F90
index f1b2737..72db78e 100644
--- a/src/Core/hco_config_mod.F90
+++ b/src/Core/hco_config_mod.F90
@@ -2138,6 +2138,8 @@ SUBROUTINE ReadSettings( HcoConfig, IU_HCO, EOF, RC )
              GridRes = '0.5x0.625'
           CASE( '025x03125', '0.25x0.3125' )
              GridRes = '0.25x0.3125'
+          CASE( '0125x015625', '0.125x0.15625' )
+             GridRes = '0.125x0.15625'
           CASE DEFAULT
              Msg = 'Improperly formatted grid resolution: ' // TRIM( GridRes )
              CALL HCO_Error( Msg, RC, Loc )
diff --git a/src/Core/hco_extlist_mod.F90 b/src/Core/hco_extlist_mod.F90
index 88f5cb2..30ac499 100644
--- a/src/Core/hco_extlist_mod.F90
+++ b/src/Core/hco_extlist_mod.F90
@@ -1579,6 +1579,8 @@ SUBROUTINE HCO_SetDefaultToken( CF, RC )
        DEF_RES = '05x0625'
     ELSE IF ( TRIM(CF%GridRes) == '0.25x0.3125' ) THEN
        DEF_RES = '025x03125'
+    ELSE IF ( TRIM(CF%GridRes) == '0.125x0.15625' ) THEN
+       DEF_RES = '0125x015625'
     ENDIF
 
     ! Wildcard character