diff --git a/pyproject.toml b/pyproject.toml
index 085f0a1bbf8..0e90eaf4858 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -209,8 +209,6 @@ ignore = [
     "PLW1641", # eq-without-hash
     "PLR0904", # too-many-public-methods
     "PLR1702", # too-many-nested-blocks
-    "UP032",   # f-string
-    "UP031",   # printf-string-formatting
 ]
 
 # Allow EN DASH (U+2013)
diff --git a/src/everest/bin/config_branch_script.py b/src/everest/bin/config_branch_script.py
index f48fe0f1474..b53453eb859 100644
--- a/src/everest/bin/config_branch_script.py
+++ b/src/everest/bin/config_branch_script.py
@@ -78,7 +78,7 @@ def _updated_initial_guess(conf_controls, opt_controls):
             if opt_control_val is None:
                 print(
                     "No generated optimization control value found for"
-                    " control {} index {}".format(variable[CK.NAME], var_index)
+                    f" control {variable[CK.NAME]} index {var_index}"
                 )
                 return None
             else:
diff --git a/src/everest/bin/main.py b/src/everest/bin/main.py
index 0b2e355c897..d71ab7c2812 100644
--- a/src/everest/bin/main.py
+++ b/src/everest/bin/main.py
@@ -54,9 +54,9 @@ def _build_args_parser():
         usage=(
             "everest <command> [<args>]\n\n"
             "The most commonly used everest commands are:\n"
-            "{commands}\n\n"
+            f"{EverestMain.methods_help()}\n\n"
             "Run everest <command> --help for more information on a command"
-        ).format(commands=EverestMain.methods_help()),
+        ),
     )
     arg_parser.add_argument("command", help="Subcommand to run")
     arg_parser.add_argument(
diff --git a/src/everest/config_file_loader.py b/src/everest/config_file_loader.py
index 023780806d9..094aa8ee5d6 100644
--- a/src/everest/config_file_loader.py
+++ b/src/everest/config_file_loader.py
@@ -60,8 +60,8 @@ def _get_definitions(configuration, configpath):
         for key, val in ERT_CONFIG_TEMPLATES.items():
             if key in defs:
                 logging.warning(
-                    "Internal key {k} specified by user as {u}. "
-                    "Overriding as {v}".format(k=key, u=defs[key], v=val)
+                    f"Internal key {key} specified by user as {defs[key]}. "
+                    f"Overriding as {val}"
                 )
             defs[key] = f"<{val}>"  # ert uses <GEO_ID> as format
     else:
diff --git a/src/everest/export.py b/src/everest/export.py
index 3044f599179..69ae317368c 100644
--- a/src/everest/export.py
+++ b/src/everest/export.py
@@ -134,9 +134,7 @@ def export_metadata(config: ExportConfig | None, optimization_output_dir: str):
                         )
             else:
                 print(
-                    "Batch {} has no available optimization data".format(
-                        md_row[MetaDataColumnNames.BATCH]
-                    )
+                    f"Batch {md_row[MetaDataColumnNames.BATCH]} has no available optimization data"
                 )
         metadata.append(md_row)
 
@@ -190,9 +188,8 @@ def check_for_errors(
         available_batches_ = available_batches(optimization_output_path)
         for batch in set(config.batches).difference(available_batches_):
             export_errors.append(
-                "Batch {} not found in optimization "
+                f"Batch {batch} not found in optimization "
                 "results. Skipping for current export."
-                "".format(batch)
             )
         config.batches = list(set(config.batches).intersection(available_batches_))
 
diff --git a/src/everest/simulator/everest_to_ert.py b/src/everest/simulator/everest_to_ert.py
index dca1c81b328..53d9fc8d07e 100644
--- a/src/everest/simulator/everest_to_ert.py
+++ b/src/everest/simulator/everest_to_ert.py
@@ -332,7 +332,7 @@ def _is_dir_all_geo(source, ever_config: EverestConfig):
         if not os.path.exists(geo_source):
             msg = (
                 "Expected source to exist for data installation, "
-                "did not find: {}".format(geo_source)
+                f"did not find: {geo_source}"
             )
             raise ValueError(msg)
 
diff --git a/src/everest/util/__init__.py b/src/everest/util/__init__.py
index a84dd7b7d19..f6366d1754d 100644
--- a/src/everest/util/__init__.py
+++ b/src/everest/util/__init__.py
@@ -31,9 +31,7 @@ def get_azure_logging_handler():
 
 
 def version_info():
-    return ("everest:'{}'\nropt:'{}'\nert:'{}'").format(
-        ert_version, ropt_version, ert_version
-    )
+    return f"everest:'{ert_version}'\nropt:'{ropt_version}'\nert:'{ert_version}'"
 
 
 def date2str(date):
diff --git a/test-data/everest/math_func/jobs/adv_distance3.py b/test-data/everest/math_func/jobs/adv_distance3.py
index ee1f5ea4e80..9946278ee51 100755
--- a/test-data/everest/math_func/jobs/adv_distance3.py
+++ b/test-data/everest/math_func/jobs/adv_distance3.py
@@ -39,7 +39,7 @@ def main(argv):
 
     if options.out:
         with open(options.out, "w", encoding="utf-8") as f:
-            f.write("%g \n" % value)
+            f.write(f"{value:g} \n")
     else:
         print(value)
 
diff --git a/test-data/everest/math_func/jobs/adv_dump_controls.py b/test-data/everest/math_func/jobs/adv_dump_controls.py
index 457c48be1fb..f170561412e 100755
--- a/test-data/everest/math_func/jobs/adv_dump_controls.py
+++ b/test-data/everest/math_func/jobs/adv_dump_controls.py
@@ -18,10 +18,10 @@ def main(argv):
     for name, indices in controls.items():
         for idx, val in indices.items():
             out_file = "{}{}{}".format(
-                opts.out_prefix, "{}-{}".format(name, idx), opts.out_suffix
+                opts.out_prefix, f"{name}-{idx}", opts.out_suffix
             )
             with open(out_file, "w", encoding="utf-8") as f:
-                f.write("%g \n" % val)
+                f.write(f"{val:g} \n")
 
 
 if __name__ == "__main__":
diff --git a/test-data/everest/math_func/jobs/discrete.py b/test-data/everest/math_func/jobs/discrete.py
index 3853760317f..a89301971d3 100755
--- a/test-data/everest/math_func/jobs/discrete.py
+++ b/test-data/everest/math_func/jobs/discrete.py
@@ -29,7 +29,7 @@ def main(argv):
 
     if options.out:
         with open(options.out, "w", encoding="utf-8") as f:
-            f.write("%g \n" % value)
+            f.write(f"{value:g} \n")
     else:
         print(value)
 
diff --git a/test-data/everest/math_func/jobs/distance3.py b/test-data/everest/math_func/jobs/distance3.py
index a7a2be714fe..ef720d04bd4 100755
--- a/test-data/everest/math_func/jobs/distance3.py
+++ b/test-data/everest/math_func/jobs/distance3.py
@@ -49,7 +49,7 @@ def main(argv):
 
     if options.out:
         with open(options.out, "w", encoding="utf-8") as f:
-            f.write("%g \n" % value)
+            f.write(f"{value:g} \n")
     else:
         print(value)
 
diff --git a/test-data/everest/math_func/jobs/dump_controls.py b/test-data/everest/math_func/jobs/dump_controls.py
index de7c431f674..7f54aca2184 100755
--- a/test-data/everest/math_func/jobs/dump_controls.py
+++ b/test-data/everest/math_func/jobs/dump_controls.py
@@ -16,9 +16,9 @@ def main(argv):
         controls = json.load(f)
 
     for k, v in controls.items():
-        out_file = "{}{}{}".format(opts.out_prefix, k, opts.out_suffix)
+        out_file = f"{opts.out_prefix}{k}{opts.out_suffix}"
         with open(out_file, "w", encoding="utf-8") as f:
-            f.write("%g \n" % v)
+            f.write(f"{v:g} \n")
 
 
 if __name__ == "__main__":
diff --git a/test-data/everest/math_func/jobs/fail_simulation.py b/test-data/everest/math_func/jobs/fail_simulation.py
index 6e2a861ca8d..c7412c65bab 100755
--- a/test-data/everest/math_func/jobs/fail_simulation.py
+++ b/test-data/everest/math_func/jobs/fail_simulation.py
@@ -20,7 +20,7 @@ def main(argv):
     options, _ = arg_parser.parse_known_args(args=argv)
 
     if options.fail in os.getcwd():
-        raise Exception("Failing %s by request!" % options.fail)
+        raise Exception(f"Failing {options.fail} by request!")
 
     time.sleep(1)
 
diff --git a/tests/everest/entry_points/test_everexport.py b/tests/everest/entry_points/test_everexport.py
index 21b64dde064..31be878aab4 100644
--- a/tests/everest/entry_points/test_everexport.py
+++ b/tests/everest/entry_points/test_everexport.py
@@ -168,12 +168,7 @@ def test_everexport_entry_no_usr_def_ecl_keys(mocked_func, cached_example):
 
     # Add export section to config file and set run_export flag to false
     with open(config_file, "a", encoding="utf-8") as f:
-        f.write(
-            "{export}:\n  {keywords}:".format(
-                export=CK.EXPORT,
-                keywords=CK.KEYWORDS,
-            )
-        )
+        f.write(f"{CK.EXPORT}:\n  {CK.KEYWORDS}:")
 
     everexport_entry([config_file])
 
@@ -209,11 +204,7 @@ def test_everexport_entry_internalized_usr_def_ecl_keys(mocked_func, cached_exam
 
     # Add export section to config file and set run_export flag to false
     with open(config_file, "a", encoding="utf-8") as f:
-        f.write(
-            "{export}:\n  {keywords}: {keys}".format(
-                export=CK.EXPORT, keywords=CK.KEYWORDS, keys=user_def_keys
-            )
-        )
+        f.write(f"{CK.EXPORT}:\n  {CK.KEYWORDS}: {user_def_keys}")
 
     everexport_entry([config_file])
 
@@ -250,11 +241,7 @@ def test_everexport_entry_non_int_usr_def_ecl_keys(mocked_func, caplog, cached_e
 
     # Add export section to config file and set run_export flag to false
     with open(config_file, "a", encoding="utf-8") as f:
-        f.write(
-            "{export}:\n  {keywords}: {keys}".format(
-                export=CK.EXPORT, keywords=CK.KEYWORDS, keys=user_def_keys
-            )
-        )
+        f.write(f"{CK.EXPORT}:\n  {CK.KEYWORDS}: {user_def_keys}")
 
     with caplog.at_level(logging.DEBUG):
         everexport_entry([config_file])
@@ -297,11 +284,7 @@ def test_everexport_entry_not_available_batches(mocked_func, caplog, cached_exam
 
     # Add export section to config file and set run_export flag to false
     with open(config_file, "a", encoding="utf-8") as f:
-        f.write(
-            "{export}:\n  {batch_key}: {batches}".format(
-                export=CK.EXPORT, batch_key=CK.BATCHES, batches=user_def_batches
-            )
-        )
+        f.write(f"{CK.EXPORT}:\n  {CK.BATCHES}: {user_def_batches}")
 
     with caplog.at_level(logging.DEBUG):
         everexport_entry([config_file])
diff --git a/tests/everest/test_config_file_loader.py b/tests/everest/test_config_file_loader.py
index 01439396f37..0544aaba712 100644
--- a/tests/everest/test_config_file_loader.py
+++ b/tests/everest/test_config_file_loader.py
@@ -80,7 +80,7 @@ def test_dependent_definitions(copy_mocked_test_data_to_tmp):
         string.ascii_lowercase[:-1], string.ascii_lowercase[1:], strict=False
     )
     for c, cdef in [*list(conseq_chars), (string.ascii_lowercase[-1], "configpath")]:
-        raw_config[CK.DEFINITIONS][c] = "r{{{{ {} }}}}".format(cdef)
+        raw_config[CK.DEFINITIONS][c] = f"r{{{{ {cdef} }}}}"
 
     with open(config_file, "w", encoding="utf-8") as f:
         yaml = YAML(typ="safe", pure=True)
diff --git a/tests/everest/test_data/mocked_test_case/jobs/controls_sum.py b/tests/everest/test_data/mocked_test_case/jobs/controls_sum.py
index 6c6018ae49f..448fd56e4ad 100755
--- a/tests/everest/test_data/mocked_test_case/jobs/controls_sum.py
+++ b/tests/everest/test_data/mocked_test_case/jobs/controls_sum.py
@@ -8,7 +8,7 @@ def main(control_group_name):
         control_group = json.load(f)
 
     with open(control_group_name + "_sum", "w", encoding="utf-8") as f_out:
-        f_out.write("%f" % sum(control_group.values()))
+        f_out.write(f"{sum(control_group.values()):f}")
 
 
 if __name__ == "__main__":
diff --git a/tests/everest/test_data/mocked_test_case/jobs/fpr_diff_mock.py b/tests/everest/test_data/mocked_test_case/jobs/fpr_diff_mock.py
index c5ce129a88f..a80523ca977 100755
--- a/tests/everest/test_data/mocked_test_case/jobs/fpr_diff_mock.py
+++ b/tests/everest/test_data/mocked_test_case/jobs/fpr_diff_mock.py
@@ -34,7 +34,7 @@ def main(argv):
 
     diff = compute_fpr_diff(sum_mock)
     with open(target_file, "w", encoding="utf-8") as out:
-        out.write("{} \n".format(diff))
+        out.write(f"{diff} \n")
 
 
 if __name__ == "__main__":
diff --git a/tests/everest/test_data/mocked_test_case/jobs/npv_function_mock.py b/tests/everest/test_data/mocked_test_case/jobs/npv_function_mock.py
index a7c3a476d3f..504e05beb1f 100755
--- a/tests/everest/test_data/mocked_test_case/jobs/npv_function_mock.py
+++ b/tests/everest/test_data/mocked_test_case/jobs/npv_function_mock.py
@@ -36,8 +36,7 @@ def compute_npv(sum):
     with open("debug.txt", "w", encoding="utf-8") as f:
         DCF = compute_dcf(fopt[0], fwpt[0], fgpt[0], fwit[0], elapsedtime[0])
         f.write(
-            "%f\t%f\t%f\t%f\t%f\t%f\n"
-            % (elapsedtime[0], fopt[0], fwpt[0], fgpt[0], fwit[0], DCF)
+            f"{elapsedtime[0]:f}\t{fopt[0]:f}\t{fwpt[0]:f}\t{fgpt[0]:f}\t{fwit[0]:f}\t{DCF:f}\n"
         )
         NPV = DCF
 
@@ -51,8 +50,7 @@ def compute_npv(sum):
             )
             NPV += DCF
             f.write(
-                "%f\t%f\t%f\t%f\t%f\t%f\n"
-                % (elapsedtime[i], fopt[i], fwpt[i], fgpt[i], fwit[i], DCF)
+                f"{elapsedtime[i]:f}\t{fopt[i]:f}\t{fwpt[i]:f}\t{fgpt[i]:f}\t{fwit[i]:f}\t{DCF:f}\n"
             )
 
     return NPV
@@ -78,7 +76,7 @@ def compute_dcf(voilp, vwaterp, vgasp, vwateri, elapsedtime):
 
 def save_object_value(object_value, target_file):
     with open(target_file, "w", encoding="utf-8") as f:
-        f.write("%g \n" % object_value)
+        f.write(f"{object_value:g} \n")
 
 
 def main(argv):
diff --git a/tests/everest/test_data/mocked_test_case/jobs/oil_prod_rate_mock.py b/tests/everest/test_data/mocked_test_case/jobs/oil_prod_rate_mock.py
index c216c11672a..122b62343fd 100755
--- a/tests/everest/test_data/mocked_test_case/jobs/oil_prod_rate_mock.py
+++ b/tests/everest/test_data/mocked_test_case/jobs/oil_prod_rate_mock.py
@@ -22,7 +22,7 @@ def main(argv):
 
     for i in range(0, len(times)):
         val = sum.get("FOPR")[i]
-        save_return_value(val, "oil_prod_rate_%03d" % i)
+        save_return_value(val, f"oil_prod_rate_{i:03d}")
 
     with open("OIL_PROD_RATE_OK", "w", encoding="utf-8") as f:
         f.write("Everything went fine here!")
diff --git a/tests/everest/test_detached.py b/tests/everest/test_detached.py
index 258d98628da..6d317d940c5 100644
--- a/tests/everest/test_detached.py
+++ b/tests/everest/test_detached.py
@@ -127,13 +127,13 @@ def test_server_status(copy_math_func_test_data_to_tmp):
     )
     status = everserver_status(everserver_status_path)
     assert status["status"] == ServerStatus.failed
-    assert status["message"] == "{}\n{}".format(err_msg_1, err_msg_2)
+    assert status["message"] == f"{err_msg_1}\n{err_msg_2}"
 
     update_everserver_status(everserver_status_path, ServerStatus.completed)
     status = everserver_status(everserver_status_path)
     assert status["status"] == ServerStatus.completed
     assert status["message"] is not None
-    assert status["message"] == "{}\n{}".format(err_msg_1, err_msg_2)
+    assert status["message"] == f"{err_msg_1}\n{err_msg_2}"
 
 
 @patch("everest.detached.server_is_running", return_value=False)
diff --git a/tests/everest/test_egg_simulation.py b/tests/everest/test_egg_simulation.py
index 1ab4838a41d..bab67a53712 100644
--- a/tests/everest/test_egg_simulation.py
+++ b/tests/everest/test_egg_simulation.py
@@ -490,7 +490,7 @@ def _generate_exp_ert_config(config_path, output_dir):
             ),
             (
                 "symlink",
-                "{config_path}/../input/files".format(config_path=config_path),
+                f"{config_path}/../input/files",
                 "files",
             ),
             (
@@ -710,7 +710,7 @@ def sweetcallbackofmine(self, *args, **kwargs):
     cgname = config.controls[0].name
     well_names = [well.name for well in config.wells]
     for wname in well_names:
-        assert "{cg}_{w}-1".format(cg=cgname, w=wname) in df
+        assert f"{cgname}_{wname}-1" in df
 
     # Check objective export
     objective_names = [objf.name for objf in config.objective_functions]
diff --git a/tests/everest/test_export.py b/tests/everest/test_export.py
index 6649911df3c..4686748df4a 100644
--- a/tests/everest/test_export.py
+++ b/tests/everest/test_export.py
@@ -311,9 +311,7 @@ def check_error(expected_error, reported_errors):
 
     check_error(
         (
-            "Non-internalized ecl keys selected for export '{keys}'." "".format(
-                keys=non_int_key
-            ),
+            f"Non-internalized ecl keys selected for export '{non_int_key}'.",
             False,
         ),
         (errors, export_ecl),
@@ -331,8 +329,8 @@ def check_error(expected_error, reported_errors):
     )
     check_error(
         (
-            "Batch {} not found in optimization results. Skipping for"
-            " current export".format(non_valid_batch),
+            f"Batch {non_valid_batch} not found in optimization results. Skipping for"
+            " current export",
             True,
         ),
         (errors, export_ecl),
diff --git a/tests/everest/test_math_func.py b/tests/everest/test_math_func.py
index 986dafac11e..54446757c2d 100644
--- a/tests/everest/test_math_func.py
+++ b/tests/everest/test_math_func.py
@@ -142,9 +142,9 @@ def test_math_func_advanced(
 
     ok_evals_0 = ok_evals[ok_evals["realization"] == 0]
     best_0 = ok_evals_0.iloc[-1]
-    assert best_0["point_{}".format(point_names[0])] == pytest.approx(x0)
-    assert best_0["point_{}".format(point_names[1])] == pytest.approx(x1)
-    assert best_0["point_{}".format(point_names[2])] == pytest.approx(x2)
+    assert best_0[f"point_{point_names[0]}"] == pytest.approx(x0)
+    assert best_0[f"point_{point_names[1]}"] == pytest.approx(x1)
+    assert best_0[f"point_{point_names[2]}"] == pytest.approx(x2)
     assert best_0["distance"] == pytest.approx(-dist_0, abs=0.001)
     assert best_0["real_avg_obj"] == pytest.approx(
         run_model.result.total_objective, abs=0.001
@@ -153,9 +153,9 @@ def test_math_func_advanced(
 
     ok_evals_1 = ok_evals[ok_evals["realization"] == 2]
     best_1 = ok_evals_1.iloc[-1]
-    assert best_1["point_{}".format(point_names[0])] == pytest.approx(x0)
-    assert best_1["point_{}".format(point_names[1])] == pytest.approx(x1)
-    assert best_1["point_{}".format(point_names[2])] == pytest.approx(x2)
+    assert best_1[f"point_{point_names[0]}"] == pytest.approx(x0)
+    assert best_1[f"point_{point_names[1]}"] == pytest.approx(x1)
+    assert best_1[f"point_{point_names[2]}"] == pytest.approx(x2)
     assert best_1["distance"] == pytest.approx(-dist_1, abs=0.001)
     assert best_1["real_avg_obj"] == pytest.approx(
         run_model.result.total_objective, abs=0.001
@@ -191,7 +191,7 @@ def test_remove_run_path(
     simulation_should_fail = "simulation_2"
     # Add to the config dictionary what simulation needs to fail
     config.forward_model[config.forward_model.index("toggle_failure")] = (
-        "toggle_failure --fail %s" % simulation_should_fail
+        f"toggle_failure --fail {simulation_should_fail}"
     )
 
     simulation_dir = config.simulation_dir
diff --git a/tests/everest/test_res_initialization.py b/tests/everest/test_res_initialization.py
index bc5c0f8dbee..259a0d19894 100644
--- a/tests/everest/test_res_initialization.py
+++ b/tests/everest/test_res_initialization.py
@@ -253,7 +253,7 @@ def test_summary_default_no_opm(copy_egg_test_data_to_tmp):
         list(everest.simulator.DEFAULT_DATA_SUMMARY_KEYS)
         + list(everest.simulator.DEFAULT_FIELD_SUMMARY_KEYS)
         + [
-            "{}:{}".format(k, w)
+            f"{k}:{w}"
             for k, w in itertools.product(
                 everest.simulator.DEFAULT_WELL_SUMMARY_KEYS, wells
             )
diff --git a/tests/everest/test_templating.py b/tests/everest/test_templating.py
index 8b5aa81f004..6a551897003 100644
--- a/tests/everest/test_templating.py
+++ b/tests/everest/test_templating.py
@@ -19,7 +19,7 @@
 def test_render_invalid(copy_template_test_data_to_tmp):
     render = everest.jobs.templating.render
 
-    prod_wells = {"PROD%d" % idx: 0.3 * idx for idx in range(4)}
+    prod_wells = {f"PROD{idx:d}": 0.3 * idx for idx in range(4)}
     prod_in = "well_drill_prod.json"
     with open(prod_in, "w", encoding="utf-8") as fout:
         json.dump(prod_wells, fout)
@@ -45,8 +45,8 @@ def test_render_invalid(copy_template_test_data_to_tmp):
 def test_render(copy_template_test_data_to_tmp):
     render = everest.jobs.templating.render
 
-    wells = {"PROD%d" % idx: 0.2 * idx for idx in range(1, 5)}
-    wells.update({"INJ%d" % idx: 1 - 0.2 * idx for idx in range(1, 5)})
+    wells = {f"PROD{idx:d}": 0.2 * idx for idx in range(1, 5)}
+    wells.update({f"INJ{idx:d}": 1 - 0.2 * idx for idx in range(1, 5)})
     wells_in = "well_drill.json"
     with open(wells_in, "w", encoding="utf-8") as fout:
         json.dump(wells, fout)
@@ -64,8 +64,8 @@ def test_render(copy_template_test_data_to_tmp):
             assert line == "----------------------------------\n"
         else:
             on_off = "on" if wells[split[0]] >= 0.5 else "off"
-            expected_string = "{} takes value {}, implying {}\n".format(
-                split[0], wells[split[0]], on_off
+            expected_string = (
+                f"{split[0]} takes value {wells[split[0]]}, implying {on_off}\n"
             )
             if idx == len(output) - 1:
                 expected_string = expected_string[:-1]
@@ -75,12 +75,12 @@ def test_render(copy_template_test_data_to_tmp):
 def test_render_multiple_input(copy_template_test_data_to_tmp):
     render = everest.jobs.templating.render
 
-    wells_north = {"PROD%d" % idx: 0.2 * idx for idx in range(1, 5)}
+    wells_north = {f"PROD{idx:d}": 0.2 * idx for idx in range(1, 5)}
     wells_north_in = "well_drill_north.json"
     with open(wells_north_in, "w", encoding="utf-8") as fout:
         json.dump(wells_north, fout)
 
-    wells_south = {"PROD%d" % idx: 1 - 0.2 * idx for idx in range(1, 5)}
+    wells_south = {f"PROD{idx:d}": 1 - 0.2 * idx for idx in range(1, 5)}
     wells_south_in = "well_drill_south.json"
     with open(wells_south_in, "w", encoding="utf-8") as fout:
         json.dump(wells_south, fout)
@@ -98,12 +98,12 @@ def test_render_executable(copy_template_test_data_to_tmp):
     assert os.access(everest.jobs.render, os.X_OK)
 
     # Dump input
-    wells_north = {"PROD%d" % idx: 0.2 * idx for idx in range(1, 5)}
+    wells_north = {f"PROD{idx:d}": 0.2 * idx for idx in range(1, 5)}
     wells_north_in = "well_drill_north.json"
     with open(wells_north_in, "w", encoding="utf-8") as fout:
         json.dump(wells_north, fout)
 
-    wells_south = {"PROD%d" % idx: 1 - 0.2 * idx for idx in range(1, 5)}
+    wells_south = {f"PROD{idx:d}": 1 - 0.2 * idx for idx in range(1, 5)}
     wells_south_in = "well_drill_south.json"
     with open(wells_south_in, "w", encoding="utf-8") as fout:
         json.dump(wells_south, fout)
@@ -238,4 +238,4 @@ def test_user_specified_data_n_template(
         contents = f.read()
     assert (
         contents == "VALUE1+VALUE2"
-    ), 'Expected contents: "VALUE1+VALUE2", found: {}'.format(contents)
+    ), f'Expected contents: "VALUE1+VALUE2", found: {contents}'
diff --git a/tests/everest/test_well_tools.py b/tests/everest/test_well_tools.py
index 0f5e43ead26..f2cde6415d5 100644
--- a/tests/everest/test_well_tools.py
+++ b/tests/everest/test_well_tools.py
@@ -188,7 +188,7 @@ def _dump_merge_data(well_data_file, additional_data_files):
     ]
 
     for idx, add_data_file in enumerate(additional_data_files):
-        prop = "property_{}".format(idx)
+        prop = f"property_{idx}"
         add_data = [
             {name: "PROD2", prop: idx * 100 + 11},
             {name: "INJECT1", prop: idx * 100 + 1},
diff --git a/tests/everest/utils/__init__.py b/tests/everest/utils/__init__.py
index b09b1a8e48a..9a4926aef8a 100644
--- a/tests/everest/utils/__init__.py
+++ b/tests/everest/utils/__init__.py
@@ -112,7 +112,7 @@ def everest_default_jobs(output_dir):
     return [
         (
             script_name,
-            os.path.join(output_dir, ".jobs", "_%s" % script_name),
+            os.path.join(output_dir, ".jobs", f"_{script_name}"),
         )
         for script_name in script_names
     ]