diff --git a/.github/workflows/run_tests.yml b/.github/workflows/run_tests.yml
index cbeb1ae..8ba6b5a 100644
--- a/.github/workflows/run_tests.yml
+++ b/.github/workflows/run_tests.yml
@@ -19,6 +19,8 @@ jobs:
         exclude:
           - os: macos-latest
             python-version: '3.8'
+          - os: windows-latest
+            python-version: '3.8'
       fail-fast: false
 
     steps:
diff --git a/src/ncas_amof_netcdf_template/util.py b/src/ncas_amof_netcdf_template/util.py
index e15dc8a..fcb2447 100644
--- a/src/ncas_amof_netcdf_template/util.py
+++ b/src/ncas_amof_netcdf_template/util.py
@@ -436,7 +436,7 @@ def update_variable(ncfile, ncfile_varname, data, qc_data_error=True):
         and "flag_values" in ncfile.variables[ncfile_varname].ncattrs()
     ):
         if not np.in1d(data, ncfile.variables[ncfile_varname].flag_values).all():
-            valid_values = list(ncfile.variables[ncfile_varname].flag_values)
+            valid_values = ncfile.variables[ncfile_varname].flag_values.tolist()
             msg = (
                 "Invalid data being added to QC variable, "
                 f"only {valid_values} are allowed."