diff --git a/pyproject.toml b/pyproject.toml
index c00908024..4291211e5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -114,6 +114,7 @@ select = [
   "NPY", # numpy specific rules
   "PL",  # pylint
   "SIM", # flake-8-simplify
+  "UP",  # pyupgrade
   "W",   # pycodestyle
 ]
 ignore = [
diff --git a/src/semeio/_docs_utils/_json_schema_2_rst.py b/src/semeio/_docs_utils/_json_schema_2_rst.py
index 7e4a40623..ab548eccf 100644
--- a/src/semeio/_docs_utils/_json_schema_2_rst.py
+++ b/src/semeio/_docs_utils/_json_schema_2_rst.py
@@ -1,5 +1,4 @@
 from copy import deepcopy
-from typing import List, Optional, Union
 
 
 def _insert_ref(schema: dict, defs: dict) -> dict:
@@ -66,8 +65,8 @@ def _create_docs(schema: dict) -> str:
 
 
 def _make_documentation(
-    schema: Union[list, dict, str],
-    required: Optional[List[str]] = None,
+    schema: list | dict | str,
+    required: list[str] | None = None,
     level: int = 0,
     preface: str = "",
     element_seperator: str = "\n\n",
diff --git a/src/semeio/fmudesign/_excel2dict.py b/src/semeio/fmudesign/_excel2dict.py
index 9a3ac53b4..1555ae685 100644
--- a/src/semeio/fmudesign/_excel2dict.py
+++ b/src/semeio/fmudesign/_excel2dict.py
@@ -83,9 +83,7 @@ def _find_geninput_sheetname(input_filename):
 
     if len(general_input_sheet) > 1:
         raise ValueError(
-            "More than one sheet with general input. Sheetnames are {} ".format(
-                general_input_sheet
-            )
+            f"More than one sheet with general input. Sheetnames are {general_input_sheet} "
         )
 
     if not general_input_sheet:
@@ -120,9 +118,7 @@ def _find_onebyone_defaults_sheet(input_filename):
             default_values_sheet.append(sheet)
     if len(default_values_sheet) > 1:
         raise ValueError(
-            "More than one sheet with default values. Sheetnames are {} ".format(
-                default_values_sheet
-            )
+            f"More than one sheet with default values. Sheetnames are {default_values_sheet} "
         )
 
     if len(default_values_sheet) == []:
@@ -175,9 +171,9 @@ def _check_designinput(dsgn_input):
         if _has_value(row.sensname):
             if row.sensname in sensitivity_names:
                 raise ValueError(
-                    "sensname '{}' was found on more than one row in designinput "
+                    f"sensname '{row.sensname}' was found on more than one row in designinput "
                     "sheet. Two sensitivities can not share the same sensname. "
-                    "Please correct this and rerun".format(row.sensname)
+                    "Please correct this and rerun"
                 )
             sensitivity_names.append(row.sensname)
 
@@ -189,10 +185,10 @@ def _check_for_mixed_sensitivities(sens_name, sens_group):
     types = sens_group.groupby("type", sort=False)
     if len(types) > 1:
         raise ValueError(
-            "The sensitivity with sensname '{}' in designinput sheet contains more "
+            f"The sensitivity with sensname '{sens_name}' in designinput sheet contains more "
             "than one sensitivity type. For each sensname all parameters must be "
             "specified using the same type (seed, scenario, dist, ref, background, "
-            "extern)".format(sens_name)
+            "extern)"
         )
 
 
@@ -393,11 +389,9 @@ def _read_defaultvalues(filename, sheetname):
     for row in default_df.itertuples():
         if str(row[0]) in default_dict:
             print(
-                "WARNING: The default value '{}' "
-                "is listed twice in the sheet '{}'. "
-                "Only the first entry will be used in output file".format(
-                    row[0], sheetname
-                )
+                f"WARNING: The default value '{row[0]}' "
+                f"is listed twice in the sheet '{sheetname}'. "
+                "Only the first entry will be used in output file"
             )
         else:
             default_dict[str(row[0])] = row[1]
@@ -432,9 +426,9 @@ def _read_dependencies(filename, sheetname, from_parameter):
                 depend_dict["to_params"][key] = depend_df[key].tolist()
     else:
         raise ValueError(
-            "Parameter {} specified to have derived parameters, "
-            "but the sheet specifying the dependencies {} does "
-            "not contain the input parameter. ".format(from_parameter, sheetname)
+            f"Parameter {from_parameter} specified to have derived parameters, "
+            f"but the sheet specifying the dependencies {sheetname} does "
+            "not contain the input parameter. "
         )
     return depend_dict
 
@@ -479,25 +473,25 @@ def _read_background(inp_filename, bck_sheet):
             )
         if not _has_value(row.dist_param1):
             raise ValueError(
-                "Parameter {} has been input "
+                f"Parameter {row.param_name} has been input "
                 "in background sheet but with empty "
-                "first distribution parameter ".format(row.param_name)
+                "first distribution parameter "
             )
         if not _has_value(row.dist_param2) and _has_value(row.dist_param3):
             raise ValueError(
-                "Parameter {} has been input in "
+                f"Parameter {row.param_name} has been input in "
                 "background sheet with "
                 'value for "dist_param3" while '
                 '"dist_param2" is empty. This is not '
-                "allowed".format(row.param_name)
+                "allowed"
             )
         if not _has_value(row.dist_param3) and _has_value(row.dist_param4):
             raise ValueError(
-                "Parameter {} has been input in "
+                f"Parameter {row.param_name} has been input in "
                 "background sheet with "
                 'value for "dist_param4" while '
                 '"dist_param3" is empty. This is not '
-                "allowed".format(row.param_name)
+                "allowed"
             )
         distparams = [
             item
@@ -545,15 +539,15 @@ def _read_scenario_sensitivity(sensgroup):
     for row in sensgroup.itertuples():
         if not _has_value(row.param_name):
             raise ValueError(
-                "Scenario sensitivity {} specified "
+                f"Scenario sensitivity {row.sensname} specified "
                 "where one line has empty parameter "
-                "name ".format(row.sensname)
+                "name "
             )
         if not _has_value(row.value1):
             raise ValueError(
-                "Parameter {} har been input "
+                f"Parameter {row.param_name} har been input "
                 'as type "scenario" but with empty '
-                "value in value1 column ".format(row.param_name)
+                "value in value1 column "
             )
         casedict1[str(row.param_name)] = row.value1
 
@@ -596,9 +590,9 @@ def _read_constants(sensgroup):
     for row in sensgroup.itertuples():
         if not _has_value(row.dist_param1):
             raise ValueError(
-                "Parameter name {} has been input "
+                f"Parameter name {row.param_name} has been input "
                 'in a sensitivity of type "seed". \n'
-                "If {} was meant to be the name of "
+                f"If {row.param_name} was meant to be the name of "
                 "the seed parameter, this is "
                 "unfortunately not allowed. "
                 "The seed parameter name is standardised "
@@ -606,9 +600,7 @@ def _read_constants(sensgroup):
                 "If you instead meant to specify a constant "
                 "value for another parameter in the seed "
                 'sensitivity, please remember "const" in '
-                'dist_name and a value in "dist_param1". '.format(
-                    row.param_name, row.param_name
-                )
+                'dist_name and a value in "dist_param1". '
             )
         distparams = row.dist_param1
         paramdict[str(row.param_name)] = [str(row.dist_name), distparams]
@@ -631,29 +623,29 @@ def _read_dist_sensitivity(sensgroup):
     for row in sensgroup.itertuples():
         if not _has_value(row.param_name):
             raise ValueError(
-                "Dist sensitivity {} specified "
+                f"Dist sensitivity {row.sensname} specified "
                 "where one line has empty parameter "
-                "name ".format(row.sensname)
+                "name "
             )
         if not _has_value(row.dist_param1):
             raise ValueError(
-                "Parameter {} has been input "
+                f"Parameter {row.param_name} has been input "
                 'as type "dist" but with empty '
-                "first distribution parameter ".format(row.param_name)
+                "first distribution parameter "
             )
         if not _has_value(row.dist_param2) and _has_value(row.dist_param3):
             raise ValueError(
-                "Parameter {} has been input with "
+                f"Parameter {row.param_name} has been input with "
                 'value for "dist_param3" while '
                 '"dist_param2" is empty. This is not '
-                "allowed".format(row.param_name)
+                "allowed"
             )
         if not _has_value(row.dist_param3) and _has_value(row.dist_param4):
             raise ValueError(
-                "Parameter {} has been input with "
+                f"Parameter {row.param_name} has been input with "
                 'value for "dist_param4" while '
                 '"dist_param3" is empty. This is not '
-                "allowed".format(row.param_name)
+                "allowed"
             )
         distparams = [
             item
diff --git a/src/semeio/fmudesign/_tornado_onebyone.py b/src/semeio/fmudesign/_tornado_onebyone.py
index c06a996de..fdc6c9237 100755
--- a/src/semeio/fmudesign/_tornado_onebyone.py
+++ b/src/semeio/fmudesign/_tornado_onebyone.py
@@ -188,7 +188,7 @@ def calc_tornadoinput(
             avg1 = 0
             print(
                 "Warning: Number of ok realizations is 0 in"
-                "sensitivity {} case1".format(sensname)
+                f"sensitivity {sensname} case1"
             )
 
         if designsummary.loc[sensno]["senstype"] == "mc":
@@ -227,7 +227,7 @@ def calc_tornadoinput(
                     avg2 = 0
                     print(
                         "Warning: Number of ok realizations is 0 in"
-                        "sensitivity {} case2".format(sensname)
+                        f"sensitivity {sensname} case2"
                     )
                 subset2name = designsummary.loc[sensno]["casename2"]
             else:
diff --git a/src/semeio/fmudesign/create_design.py b/src/semeio/fmudesign/create_design.py
index fa50b6f11..740486cbe 100644
--- a/src/semeio/fmudesign/create_design.py
+++ b/src/semeio/fmudesign/create_design.py
@@ -13,9 +13,11 @@
 # are irrelevant and would only confuse users. We suppress them by redirecting
 # stdout/stderr during import.
 # https://github.com/cvxpy/cvxpy/issues/2470
-with open(os.devnull, "w") as devnull, contextlib.redirect_stdout(
-    devnull
-), contextlib.redirect_stderr(devnull):
+with (
+    open(os.devnull, "w") as devnull,
+    contextlib.redirect_stdout(devnull),
+    contextlib.redirect_stderr(devnull),
+):
     import cvxpy as cp
 
 import numpy as np
@@ -330,7 +332,7 @@ def to_xlsx(
             print(
                 "Warning: Output filename did not have extension .xlsx "
                 "but the export format is Excel .xlsx .  "
-                "Changing outputname to {}".format(filename)
+                f"Changing outputname to {filename}"
             )
 
         xlsxwriter = pd.ExcelWriter(filename, engine="openpyxl")
@@ -383,7 +385,7 @@ def add_seeds(self, seeds, max_reals):
                 "Valid choices for seeds are None, "
                 '"default" or an existing filename. '
                 "Neither was found in this case. seeds "
-                "had been specified as {} .".format(seeds)
+                f"had been specified as {seeds} ."
             )
 
     def add_background(
@@ -446,20 +448,16 @@ def _fill_with_background_values(self):
                         if len(temp_df) > len(self.backgroundvalues):
                             raise ValueError(
                                 "Provided number of background values "
-                                "{} is smaller than number"
-                                " of realisations for sensitivity {}".format(
-                                    len(self.backgroundvalues), sensname
-                                )
+                                f"{len(self.backgroundvalues)} is smaller than number"
+                                f" of realisations for sensitivity {sensname}"
                             )
                     elif len(temp_df) > len(self.backgroundvalues):
                         print(
                             "Provided number of background values "
-                            "({}) is smaller than number"
-                            " of realisations for sensitivity {}"
-                            " and parameter {}. "
-                            "Will be filled with default values.".format(
-                                len(self.backgroundvalues), sensname, key
-                            )
+                            f"({len(self.backgroundvalues)}) is smaller than number"
+                            f" of realisations for sensitivity {sensname}"
+                            f" and parameter {key}. "
+                            "Will be filled with default values."
                         )
                 existing_values = result_values.copy()
                 result_values = pd.concat([existing_values, temp_df])
@@ -490,13 +488,13 @@ def _fill_derived_params(self, depend_dict):
                         )
                     if self.designvalues[param].isnull().any():
                         raise ValueError(
-                            "Column for derived parameter {} "
+                            f"Column for derived parameter {param} "
                             "contains NaN. Check input "
                             "defining dependencies. "
                             "Could be Wrong values or that "
                             "values for input variable  in "
                             "dependencies sheet "
-                            "should be specified as strings.".format(param)
+                            "should be specified as strings."
                         )
 
     def _add_dist_background(
@@ -603,7 +601,7 @@ def generate(self, realnums, seedname, seedvalues, parameters):
                     raise ValueError(
                         'A sensitivity of type "seed" can only have '
                         "additional parameters where dist_name is "
-                        '"const". Check sensitivity {}"'.format(self.sensname)
+                        f'"const". Check sensitivity {self.sensname}"'
                     )
                 self.sensvalues[key] = constant
 
@@ -967,9 +965,9 @@ def generate(self, realnums, filename, parameters, seedvalues):
         extern_values = _parameters_from_extern(filename)
         if len(realnums) > len(extern_values):
             raise ValueError(
-                "Number of realisations {} specified for "
-                "sensitivity {} is larger than rows in "
-                "file {}".format(len(realnums), self.sensname, filename)
+                f"Number of realisations {len(realnums)} specified for "
+                f"sensitivity {self.sensname} is larger than rows in "
+                f"file {filename}"
             )
         for param in parameters:
             if param in extern_values:
@@ -1064,7 +1062,7 @@ def _printwarning(corr_group_name):
         "Using designinput sheets where "
         "corr_sheet is only specified for one parameter "
         "will cause non-correlated parameters .\n"
-        "ONLY ONE PARAMETER WAS SPECIFIED TO USE CORR_SHEET {}\n"
+        f"ONLY ONE PARAMETER WAS SPECIFIED TO USE CORR_SHEET {corr_group_name}\n"
         "\n"
         "Note change in how correlated parameters are specified \n"
         "from fmudeisgn version 1.0.1 in August 2019 :\n"
@@ -1079,5 +1077,4 @@ def _printwarning(corr_group_name):
         "one-by-one-sensitivities\n"
         "\n"
         "####################################################\n"
-        "".format(corr_group_name)
     )
diff --git a/src/semeio/fmudesign/design_distributions.py b/src/semeio/fmudesign/design_distributions.py
index da9e2feee..ae64a2c81 100644
--- a/src/semeio/fmudesign/design_distributions.py
+++ b/src/semeio/fmudesign/design_distributions.py
@@ -4,7 +4,6 @@
 
 import re
 from pathlib import Path
-from typing import Union
 
 import numpy as np
 import pandas as pd
@@ -299,7 +298,7 @@ def draw_values_triangular(dist_parameters, numreals, rng, normalscoresamples=No
     if high == low:  # collapsed distribution
         print(
             "Low and high parameters for triangular distribution"
-            " are equal. Using constant {}".format(low)
+            f" are equal. Using constant {low}"
         )
         if normalscoresamples is not None:
             values = scipy.stats.uniform.ppf(
@@ -355,7 +354,7 @@ def draw_values_pert(dist_parameters, numreals, rng, normalscoresamples=None):
     if high == low:  # collapsed distribution
         print(
             "Low and high parameters for pert distribution"
-            " are equal. Using constant {}".format(low)
+            f" are equal. Using constant {low}"
         )
         if normalscoresamples is not None:
             values = scipy.stats.uniform.ppf(
@@ -515,9 +514,7 @@ def is_number(teststring):
         return False
 
 
-def read_correlations(
-    excel_filename: Union[str, Path], corr_sheet: str
-) -> pd.DataFrame:
+def read_correlations(excel_filename: str | Path, corr_sheet: str) -> pd.DataFrame:
     """Reading correlation info for a
     monte carlo sensitivity
 
diff --git a/src/semeio/fmudesign/fmudesignrunner.py b/src/semeio/fmudesign/fmudesignrunner.py
index 25c0b6185..e0bc30e22 100644
--- a/src/semeio/fmudesign/fmudesignrunner.py
+++ b/src/semeio/fmudesign/fmudesignrunner.py
@@ -78,14 +78,14 @@ def main():
 
     if isinstance(args.config, str):
         if not Path(args.config).is_file():
-            raise IOError(f"Input file {args.config} does not exist")
+            raise OSError(f"Input file {args.config} does not exist")
         input_dict = excel2dict_design(args.config, sheetnames)
 
     if args.config == args.destination:
-        raise IOError(
-            'Identical name "{}" have been provided for the input'
+        raise OSError(
+            f'Identical name "{args.config}" have been provided for the input'
             "file and the output file. "
-            " Exiting.....".format(args.config)
+            " Exiting....."
         )
 
     design = DesignMatrix()
diff --git a/src/semeio/forward_models/__init__.py b/src/semeio/forward_models/__init__.py
index 0486c1f4b..2ad92ad60 100644
--- a/src/semeio/forward_models/__init__.py
+++ b/src/semeio/forward_models/__init__.py
@@ -1,5 +1,3 @@
-from typing import Optional
-
 from ert import (
     ForwardModelStepDocumentation,
     ForwardModelStepJSON,
@@ -34,7 +32,7 @@ def validate_pre_experiment(self, fm_step_json: ForwardModelStepJSON) -> None:
         return fm_step_json
 
     @staticmethod
-    def documentation() -> Optional[ForwardModelStepDocumentation]:
+    def documentation() -> ForwardModelStepDocumentation | None:
         return ForwardModelStepDocumentation(
             category="utility.templating",
             source_package="semeio",
@@ -73,7 +71,7 @@ def validate_pre_experiment(self, fm_step_json: ForwardModelStepJSON) -> None:
         return fm_step_json
 
     @staticmethod
-    def documentation() -> Optional[ForwardModelStepDocumentation]:
+    def documentation() -> ForwardModelStepDocumentation | None:
         return ForwardModelStepDocumentation(
             category="utility.templating",
             source_package="semeio",
@@ -112,7 +110,7 @@ def __init__(self):
         )
 
     @staticmethod
-    def documentation() -> Optional[ForwardModelStepDocumentation]:
+    def documentation() -> ForwardModelStepDocumentation | None:
         return ForwardModelStepDocumentation(
             category="utility.transformation",
             source_package="semeio",
@@ -167,7 +165,7 @@ def __init__(self):
         )
 
     @staticmethod
-    def documentation() -> Optional[ForwardModelStepDocumentation]:
+    def documentation() -> ForwardModelStepDocumentation | None:
         return ForwardModelStepDocumentation(
             category="modelling.surface",
             source_package="semeio",
@@ -204,7 +202,7 @@ def __init__(self):
         )
 
     @staticmethod
-    def documentation() -> Optional[ForwardModelStepDocumentation]:
+    def documentation() -> ForwardModelStepDocumentation | None:
         return ForwardModelStepDocumentation(
             category="modelling.reservoir",
             source_package="semeio",
@@ -235,7 +233,7 @@ def __init__(self):
         )
 
     @staticmethod
-    def documentation() -> Optional[ForwardModelStepDocumentation]:
+    def documentation() -> ForwardModelStepDocumentation | None:
         return ForwardModelStepDocumentation(
             category="utility.file_system",
             source_package="semeio",
@@ -254,7 +252,7 @@ def __init__(self):
         )
 
     @staticmethod
-    def documentation() -> Optional[ForwardModelStepDocumentation]:
+    def documentation() -> ForwardModelStepDocumentation | None:
         return ForwardModelStepDocumentation(
             category="utility.file_system",
             source_package="semeio",
@@ -274,7 +272,7 @@ def __init__(self):
         )
 
     @staticmethod
-    def documentation() -> Optional[ForwardModelStepDocumentation]:
+    def documentation() -> ForwardModelStepDocumentation | None:
         return ForwardModelStepDocumentation(
             category="utility.file_system",
             source_package="semeio",
diff --git a/src/semeio/forward_models/design2params/design2params.py b/src/semeio/forward_models/design2params/design2params.py
index 5add438d3..c02d145c6 100644
--- a/src/semeio/forward_models/design2params/design2params.py
+++ b/src/semeio/forward_models/design2params/design2params.py
@@ -252,11 +252,11 @@ def _invalid_design_realizations(design_matrix):
     :raises: SystemExit if some parameter names are not allowed
     """
 
-    empty_cell_coords = list(zip(*np.where(pd.isna(design_matrix))))
+    empty_cell_coords = list(zip(*np.where(pd.isna(design_matrix)), strict=False))
 
     empties = [
         f"Realization {i}, column {design_matrix.columns[j]}"
-        for i, j in zip(*np.where(pd.isna(design_matrix)))
+        for i, j in zip(*np.where(pd.isna(design_matrix)), strict=False)
     ]
     if len(empties) > 0:
         logger.warning(f"Design matrix contains empty cells {empties}")
diff --git a/src/semeio/forward_models/design_kw/design_kw.py b/src/semeio/forward_models/design_kw/design_kw.py
index 060306b2a..bb369a98e 100644
--- a/src/semeio/forward_models/design_kw/design_kw.py
+++ b/src/semeio/forward_models/design_kw/design_kw.py
@@ -1,7 +1,7 @@
 import logging
 import re
 import shlex
-from typing import Dict, List, Mapping
+from collections.abc import Mapping
 
 from ert import ForwardModelStepWarning
 
@@ -58,8 +58,8 @@ def run(
 
 
 def find_matching_errors(
-    line: str, template_file_name: str, template: List[str]
-) -> List[str]:
+    line: str, template_file_name: str, template: list[str]
+) -> list[str]:
     errors = []
     for unmatched in unmatched_templates(line):
         if is_perl(template_file_name, template):
@@ -83,7 +83,7 @@ def is_perl(file_name, template):
     return file_name.endswith(".pl") or template[0].find("perl") != -1
 
 
-def is_xml(file_name: str, template: List[str]) -> bool:
+def is_xml(file_name: str, template: list[str]) -> bool:
     return file_name.endswith(".xml") or template[0].find("?xml") != -1
 
 
@@ -100,7 +100,7 @@ def is_comment(line):
     return ecl_comment_pattern.search(line) or std_comment_pattern.search(line)
 
 
-def extract_key_value(parameters: List[str]) -> Dict[str, str]:
+def extract_key_value(parameters: list[str]) -> dict[str, str]:
     """Parses a list of strings, looking for key-value pairs pr. line
     separated by whitespace, into a dictionary.
 
diff --git a/src/semeio/forward_models/overburden_timeshift/ots.py b/src/semeio/forward_models/overburden_timeshift/ots.py
index 0fb85621b..a8c8ae1a8 100644
--- a/src/semeio/forward_models/overburden_timeshift/ots.py
+++ b/src/semeio/forward_models/overburden_timeshift/ots.py
@@ -432,7 +432,10 @@ def _vintages_name_date(vintage_pairs):
             vintages_name.append(f"S{i}")
 
         Vintage = namedtuple("Vintages", "name date")
-        return [Vintage(name, date) for name, date in zip(vintages_name, vintages_date)]
+        return [
+            Vintage(name, date)
+            for name, date in zip(vintages_name, vintages_date, strict=False)
+        ]
 
     def _report(self, func_name, base, monitor, num_points_calculated):
         if self._convention == 1:
diff --git a/src/semeio/forward_models/overburden_timeshift/ots_config.py b/src/semeio/forward_models/overburden_timeshift/ots_config.py
index e9800fdbc..65e716475 100644
--- a/src/semeio/forward_models/overburden_timeshift/ots_config.py
+++ b/src/semeio/forward_models/overburden_timeshift/ots_config.py
@@ -1,13 +1,12 @@
 from datetime import date
 from pathlib import Path
-from typing import TYPE_CHECKING, List, Literal, Optional
+from typing import TYPE_CHECKING, Annotated, Literal, Self
 
 from pydantic import BaseModel, Field, conlist, field_validator, model_validator
 from resdata.resfile import ResdataFile
-from typing_extensions import Annotated, Self
 
 if TYPE_CHECKING:
-    ConstrainedList = List[date]
+    ConstrainedList = list[date]
 else:
     ConstrainedList = conlist(date, min_length=2, max_length=2)
 
@@ -23,7 +22,7 @@ class Vintages(BaseModel):
     """
 
     ts_simple: Annotated[
-        List[ConstrainedList],
+        list[ConstrainedList],
         Field(
             description=(
                 "Simple TimeShift geertsma algorithm. "
@@ -32,17 +31,17 @@ class Vintages(BaseModel):
         ),
     ] = []
     ts: Annotated[
-        List[ConstrainedList],
+        list[ConstrainedList],
         Field(
             description="TimeShift geertsma algorithm, which uses velocity, very slow"
         ),
     ] = []
     ts_rporv: Annotated[
-        List[ConstrainedList],
+        list[ConstrainedList],
         Field(description="Delta pressure multiplied by cell volume, relatively fast"),
     ] = []
     dpv: Annotated[
-        List[ConstrainedList],
+        list[ConstrainedList],
         Field(
             description=(
                 "Calculates timeshift without using velocity. The velocity is only "
@@ -127,7 +126,7 @@ class OTSConfig(BaseModel):
         ),
     ]
     horizon: Annotated[
-        Optional[str],
+        str | None,
         Field(
             None,
             description=(
@@ -138,7 +137,7 @@ class OTSConfig(BaseModel):
     ]
     eclbase: Annotated[str, Field(description="Path to the Eclipse case")]
     vintages_export_file: Annotated[
-        Optional[str],
+        str | None,
         Field(
             None,
             description="Path to resulting text file, which contains all computed "
@@ -146,7 +145,7 @@ class OTSConfig(BaseModel):
         ),
     ]
     velocity_model: Annotated[
-        Optional[str],
+        str | None,
         Field(None, description="Path to segy file containing the velocity field"),
     ]
     mapaxes: Annotated[
diff --git a/src/semeio/forward_models/rft/utility.py b/src/semeio/forward_models/rft/utility.py
index dc88a9357..0aa350685 100644
--- a/src/semeio/forward_models/rft/utility.py
+++ b/src/semeio/forward_models/rft/utility.py
@@ -3,7 +3,6 @@
 import os
 import warnings
 from pathlib import Path
-from typing import List, Tuple
 
 from resdata.grid import Grid
 from resdata.rft import ResdataRFTFile
@@ -23,7 +22,7 @@ def existing_directory(path):
 
 def load_and_parse_well_time_file(
     filename: str,
-) -> List[Tuple[str, datetime.date, int]]:
+) -> list[tuple[str, datetime.date, int]]:
     """
     Reads and parses a file from disk, supporting 2 formats:
 
diff --git a/src/semeio/hook_implementations/forward_models.py b/src/semeio/hook_implementations/forward_models.py
index 3d0a2bc32..6d96c1e8d 100644
--- a/src/semeio/hook_implementations/forward_models.py
+++ b/src/semeio/hook_implementations/forward_models.py
@@ -1,5 +1,4 @@
 import importlib
-from typing import Dict
 
 import ert
 import importlib_resources
@@ -22,7 +21,7 @@ def _remove_suffix(string: str, suffix: str) -> str:
     return string[: -len(suffix)]
 
 
-def _get_forward_models_from_directory(directory: str) -> Dict[str, str]:
+def _get_forward_models_from_directory(directory: str) -> dict[str, str]:
     resource_directory_ref = importlib_resources.files("semeio") / directory
 
     all_files = []
diff --git a/tests/communication/unit/test_semeio_script.py b/tests/communication/unit/test_semeio_script.py
index d59f95586..fc0b42333 100644
--- a/tests/communication/unit/test_semeio_script.py
+++ b/tests/communication/unit/test_semeio_script.py
@@ -90,7 +90,7 @@ def assert_log(messages, log_file):
         log_data = file.readlines()
 
     assert len(messages) == len(log_data)
-    for msg, log_entry in zip(messages, log_data):
+    for msg, log_entry in zip(messages, log_data, strict=False):
         assert msg in log_entry
 
 
diff --git a/tests/fmudesign/test_excel2dict.py b/tests/fmudesign/test_excel2dict.py
index 798de3167..42c3a4247 100644
--- a/tests/fmudesign/test_excel2dict.py
+++ b/tests/fmudesign/test_excel2dict.py
@@ -75,7 +75,7 @@ def test_excel2dict_design(tmpdir, monkeypatch):
     # Dump to yaml:
     inputdict_to_yaml(dict_design, "dictdesign.yaml")
     assert os.path.exists("dictdesign.yaml")
-    with open("dictdesign.yaml", "r", encoding="utf-8") as inputfile:
+    with open("dictdesign.yaml", encoding="utf-8") as inputfile:
         assert "RMS_SEED" in inputfile.read()
 
 
diff --git a/tests/forward_models/rft/test_gendata_rft.py b/tests/forward_models/rft/test_gendata_rft.py
index bbc5e7549..005acdd4b 100644
--- a/tests/forward_models/rft/test_gendata_rft.py
+++ b/tests/forward_models/rft/test_gendata_rft.py
@@ -532,8 +532,7 @@ def test_ert_setup_one_well_one_rft_point(tmpdir):
     # (assert on the return code further down)
     result = subprocess.run(
         ["ert", "ensemble_smoother", "--target-case", "default_%d", "config.ert"],
-        stdout=subprocess.PIPE,
-        stderr=subprocess.PIPE,
+        capture_output=True,
         check=False,
     )
     stdouterr = result.stdout.decode() + result.stderr.decode()
@@ -658,8 +657,7 @@ def test_ert_setup_one_well_two_points_different_time_and_depth(tmpdir):
     # (assert on the return code further down)
     result = subprocess.run(
         ["ert", "ensemble_smoother", "--target-case", "default_%d", "config.ert"],
-        stdout=subprocess.PIPE,
-        stderr=subprocess.PIPE,
+        capture_output=True,
         check=False,
     )
     stdouterr = result.stdout.decode() + result.stderr.decode()
@@ -701,7 +699,7 @@ def _assert_almost_equal_line_by_line(file1, file2):
 
     assert len(file1_content) == len(file2_content)
 
-    for line1, line2 in zip(file1_content, file2_content):
+    for line1, line2 in zip(file1_content, file2_content, strict=False):
         try:
             line1, line2 = float(line1), float(line2)
         except ValueError:
diff --git a/tests/forward_models/rft/test_trajectory.py b/tests/forward_models/rft/test_trajectory.py
index 6f534fef7..82fab22f8 100644
--- a/tests/forward_models/rft/test_trajectory.py
+++ b/tests/forward_models/rft/test_trajectory.py
@@ -100,7 +100,7 @@ def test_load(fname):
     trajectory = Trajectory.load_from_file(fname)
 
     for expected_utmx, trajectorypoint in zip(
-        expected_utmxs, trajectory.trajectory_points
+        expected_utmxs, trajectory.trajectory_points, strict=False
     ):
         assert trajectorypoint.utm_x == expected_utmx
 
diff --git a/tests/forward_models/rft/test_well_and_time.py b/tests/forward_models/rft/test_well_and_time.py
index 4aade4c55..4334d8791 100644
--- a/tests/forward_models/rft/test_well_and_time.py
+++ b/tests/forward_models/rft/test_well_and_time.py
@@ -58,7 +58,7 @@ def test_load():
         well_times = load_and_parse_well_time_file(fname)
 
         for (exp_wname, exp_wtime, exp_report), (wname, wtime, report) in zip(
-            expected_results, well_times
+            expected_results, well_times, strict=False
         ):
             assert wname == exp_wname
             assert wtime == exp_wtime
@@ -89,7 +89,7 @@ def test_invalid_load():
         "non_existing",
     ]
 
-    for fname, error in zip(fnames, errors):
+    for fname, error in zip(fnames, errors, strict=False):
         with pytest.raises(argparse.ArgumentTypeError) as msgcontext:
             load_and_parse_well_time_file(fname)
         assert error in msgcontext.value.args[0]
diff --git a/tests/forward_models/rft/test_zonemap.py b/tests/forward_models/rft/test_zonemap.py
index eacb7e668..45875e762 100644
--- a/tests/forward_models/rft/test_zonemap.py
+++ b/tests/forward_models/rft/test_zonemap.py
@@ -88,7 +88,7 @@ def test_invalid_load():
         "non_existing",
     ]
 
-    for fname, error in zip(fnames, errors):
+    for fname, error in zip(fnames, errors, strict=False):
         with pytest.raises(argparse.ArgumentTypeError) as msgcontext:
             ZoneMap.load_and_parse_zonemap_file(fname)
         assert error in msgcontext.value.args[0]