diff --git a/conanfile.py b/conanfile.py
index abdebc30..76b50460 100644
--- a/conanfile.py
+++ b/conanfile.py
@@ -28,17 +28,11 @@ from conan.errors import ConanInvalidConfiguration
 from conan.tools.build import can_run, default_cppstd, valid_min_cppstd
 from conan.tools.cmake import CMake, CMakeDeps, CMakeToolchain, cmake_layout
 from conan.tools.files import copy, load, rmdir
+from conan.tools.scm import Version
 
 required_conan_version = ">=2.0.0"
 
 
-def loose_lt_semver(v1, v2):
-    lv1 = [int(v) for v in v1.split(".")]
-    lv2 = [int(v) for v in v2.split(".")]
-    min_length = min(len(lv1), len(lv2))
-    return lv1[:min_length] < lv2[:min_length]
-
-
 class MPUnitsConan(ConanFile):
     name = "mp-units"
     homepage = "https://github.com/mpusz/mp-units"
@@ -61,22 +55,21 @@ class MPUnitsConan(ConanFile):
     url = "https://github.com/mpusz/mp-units"
     settings = "os", "arch", "compiler", "build_type"
     options = {
-        "cxx_modules": ["auto", True, False],
-        "std_format": ["auto", True, False],
-        "string_view_ret": ["auto", True, False],
-        "no_crtp": ["auto", True, False],
+        "cxx_modules": [True, False],
+        "std_format": [True, False],
+        "string_view_ret": [True, False],
+        "no_crtp": [True, False],
         "contracts": ["none", "gsl-lite", "ms-gsl"],
         "freestanding": [True, False],
     }
     default_options = {
-        "cxx_modules": "auto",
-        "std_format": "auto",
-        "string_view_ret": "auto",
-        "no_crtp": "auto",
+        # "cxx_modules" default set in config_options()
+        # "std_format" default set in config_options()
+        # "string_view_ret" default set in config_options()
+        # "no_crtp" default set in config_options()
         "contracts": "gsl-lite",
-        "freestanding": "False",
+        "freestanding": False,
     }
-    tool_requires = "cmake/[>=3.29]"
     implements = "auto_header_only"
     exports = "LICENSE.md"
     exports_sources = (
@@ -94,7 +87,7 @@ class MPUnitsConan(ConanFile):
     def _feature_compatibility(self):
         return {
             "minimum_support": {
-                "std": "20",
+                "min_cppstd": "20",
                 "compiler": {
                     "gcc": "12",
                     "clang": "16",
@@ -103,7 +96,7 @@ class MPUnitsConan(ConanFile):
                 },
             },
             "std_format": {
-                "std": "20",
+                "min_cppstd": "20",
                 "compiler": {
                     "gcc": "13",
                     "clang": "17",
@@ -112,15 +105,15 @@ class MPUnitsConan(ConanFile):
                 },
             },
             "cxx_modules": {
-                "std": "20",
-                "compiler": {"gcc": "14", "clang": "17", "apple-clang": "", "msvc": ""},
+                "min_cppstd": "20",
+                "compiler": {"gcc": "", "clang": "17", "apple-clang": "", "msvc": ""},
             },
             "static_constexpr_vars_in_constexpr_func": {
-                "std": "23",
+                "min_cppstd": "23",
                 "compiler": {"gcc": "13", "clang": "17", "apple-clang": "", "msvc": ""},
             },
             "explicit_this": {
-                "std": "23",
+                "min_cppstd": "23",
                 "compiler": {
                     "gcc": "14",
                     "clang": "18",
@@ -139,15 +132,30 @@ class MPUnitsConan(ConanFile):
             "no_crtp": "explicit_this",
         }
 
+    def _set_default_option(self, name):
+        compiler = self.settings.compiler
+        feature_name = self._option_feature_map[name]
+        feature = self._feature_compatibility[feature_name]
+        min_version = feature["compiler"].get(str(compiler))
+        setattr(
+            self.options,
+            name,
+            bool(
+                min_version
+                and Version(compiler.version) >= min_version
+                and valid_min_cppstd(self, feature["min_cppstd"])
+            ),
+        )
+
     def _check_feature_supported(self, name, feature_name=name):
         compiler = self.settings.compiler
         cppstd = compiler.get_safe("cppstd", default_cppstd(self))
         feature = self._feature_compatibility[feature_name]
 
         # check C++ version
-        if not valid_min_cppstd(self, feature["std"]):
+        if not valid_min_cppstd(self, feature["min_cppstd"]):
             raise ConanInvalidConfiguration(
-                f"'{name}' requires at least cppstd={feature['std']} ({cppstd} in use)",
+                f"'{name}' requires at least cppstd={feature['min_cppstd']} ({cppstd} in use)",
             )
 
         # check compiler version
@@ -157,40 +165,17 @@ class MPUnitsConan(ConanFile):
             return
         if min_version == "":
             raise ConanInvalidConfiguration(
-                f"'{name}' is not yet supported by any known {compiler} compiler"
+                f"'{name}' is not yet supported by any known {compiler} version"
             )
-        if loose_lt_semver(str(compiler.version), min_version):
+        if Version(compiler.version) < min_version:
             raise ConanInvalidConfiguration(
                 f"'{name}' requires at least {compiler}-{min_version} ({compiler}-{compiler.version} in use)"
             )
 
-    def _is_feature_enabled(self, name):
-        compiler = self.settings.compiler
-        opt = self.options.get_safe(name)
-        feature_name = self._option_feature_map[name]
-        feature = self._feature_compatibility[feature_name]
-        min_version = feature["compiler"].get(str(compiler))
-        return bool(
-            opt == True
-            or (
-                opt == "auto"
-                and min_version
-                and not loose_lt_semver(str(compiler.version), min_version)
-            )
-        )
-
     @property
     def _build_all(self):
         return bool(self.conf.get("user.mp-units.build:all", default=False))
 
-    @property
-    def _build_cxx_modules(self):
-        return self._is_feature_enabled("cxx_modules")
-
-    @property
-    def _use_fmtlib(self):
-        return not self._is_feature_enabled("std_format")
-
     @property
     def _skip_la(self):
         return bool(self.conf.get("user.mp-units.build:skip_la", default=False))
@@ -206,16 +191,25 @@ class MPUnitsConan(ConanFile):
         ).group(1)
         self.version = version.strip()
 
+    def config_options(self):
+        for key in self._option_feature_map.keys():
+            self._set_default_option(key)
+
+    def configure(self):
+        if self.options.freestanding:
+            self.options.rm_safe("std_format")
+
     def requirements(self):
         if not self.options.freestanding:
             if self.options.contracts == "gsl-lite":
                 self.requires("gsl-lite/0.41.0")
             elif self.options.contracts == "ms-gsl":
                 self.requires("ms-gsl/4.0.0")
-            if self._use_fmtlib:
+            if not self.options.std_format:
                 self.requires("fmt/10.2.1")
 
     def build_requirements(self):
+        self.tool_requires("cmake/[>=3.29 <4]")
         if self._build_all:
             if not self.options.freestanding:
                 self.test_requires("catch2/3.5.1")
@@ -244,21 +238,17 @@ class MPUnitsConan(ConanFile):
             tc.cache_variables["MP_UNITS_DEV_BUILD_LA"] = not self._skip_la
             if self._run_clang_tidy:
                 tc.cache_variables["MP_UNITS_DEV_CLANG_TIDY"] = True
-        if self._build_cxx_modules:
+        if self.options.cxx_modules:
             tc.cache_variables["CMAKE_CXX_SCAN_FOR_MODULES"] = True
-            tc.cache_variables["MP_UNITS_BUILD_CXX_MODULES"] = str(
-                self.options.cxx_modules
-            ).upper()
+            tc.cache_variables["MP_UNITS_BUILD_CXX_MODULES"] = True
         if self.options.freestanding:
             tc.cache_variables["MP_UNITS_API_FREESTANDING"] = True
         else:
-            tc.cache_variables["MP_UNITS_API_STD_FORMAT"] = str(
-                self.options.std_format
-            ).upper()
-        tc.cache_variables["MP_UNITS_API_STRING_VIEW_RET"] = str(
+            tc.cache_variables["MP_UNITS_API_STD_FORMAT"] = self.options.std_format
+        tc.cache_variables["MP_UNITS_API_STRING_VIEW_RET"] = (
             self.options.string_view_ret
-        ).upper()
-        tc.cache_variables["MP_UNITS_API_NO_CRTP"] = str(self.options.no_crtp).upper()
+        )
+        tc.cache_variables["MP_UNITS_API_NO_CRTP"] = self.options.no_crtp
         tc.cache_variables["MP_UNITS_API_CONTRACTS"] = str(
             self.options.contracts
         ).upper()
@@ -269,7 +259,8 @@ class MPUnitsConan(ConanFile):
     def build(self):
         cmake = CMake(self)
         cmake.configure(build_script_folder=None if self._build_all else "src")
-        cmake.build()
+        if self._build_all or self.options.cxx_modules:
+            cmake.build()
         if self._build_all:
             cmake.build(target="all_verify_interface_header_sets")
             if can_run(self):
@@ -300,20 +291,17 @@ class MPUnitsConan(ConanFile):
             self.cpp_info.components["core"].defines.append("MP_UNITS_API_CONTRACTS=3")
 
         # handle API options
-        if self.options.string_view_ret != "auto":
-            self.cpp_info.components["core"].defines.append(
-                "MP_UNITS_API_STRING_VIEW_RET="
-                + str(int(self.options.string_view_ret == True))
-            )
-        if self.options.no_crtp != "auto":
-            self.cpp_info.components["core"].defines.append(
-                "MP_UNITS_API_NO_CRTP=" + str(int(self.options.no_crtp == True))
-            )
-        if self.options.std_format != "auto":
-            self.cpp_info.components["core"].defines.append(
-                "MP_UNITS_API_STD_FORMAT=" + str(int(self.options.std_format == True))
-            )
-        if self._use_fmtlib:
+        self.cpp_info.components["core"].defines.append(
+            "MP_UNITS_API_STRING_VIEW_RET="
+            + str(int(self.options.string_view_ret == True))
+        )
+        self.cpp_info.components["core"].defines.append(
+            "MP_UNITS_API_NO_CRTP=" + str(int(self.options.no_crtp == True))
+        )
+        self.cpp_info.components["core"].defines.append(
+            "MP_UNITS_API_STD_FORMAT=" + str(int(self.options.std_format == True))
+        )
+        if not self.options.std_format:
             self.cpp_info.components["core"].requires.append("fmt::fmt")
 
         # handle hosted configuration
diff --git a/docs/getting_started/installation_and_usage.md b/docs/getting_started/installation_and_usage.md
index b34f9f3b..d852e80f 100644
--- a/docs/getting_started/installation_and_usage.md
+++ b/docs/getting_started/installation_and_usage.md
@@ -231,7 +231,7 @@ tools.build:compiler_executables={"c": "gcc-12", "cpp": "g++-12"}
 
 [`cxx_modules`](#cxx_modules){ #cxx_modules }
 
-:   [:octicons-tag-24: 2.2.0][conan C++ modules support] · :octicons-milestone-24: `auto`/`True`/`False` (Default: `auto`)
+:   [:octicons-tag-24: 2.2.0][conan C++ modules support] · :octicons-milestone-24: `True`/`False` (Default: automatically determined from settings)
 
     Configures CMake to add C++ modules to the list of default targets.
 
@@ -239,7 +239,7 @@ tools.build:compiler_executables={"c": "gcc-12", "cpp": "g++-12"}
 
 [`std_format`](#std_format){ #std_format }
 
-:   [:octicons-tag-24: 2.2.0][conan std::format support] · :octicons-milestone-24: `auto`/`True`/`False` (Default: `auto`)
+:   [:octicons-tag-24: 2.2.0][conan std::format support] · :octicons-milestone-24: `True`/`False` (Default: automatically determined from settings)
 
     Enables the usage of [`std::format`](https://en.cppreference.com/w/cpp/utility/format/format)
     and associated facilities for text formatting. If it is not supported, then
@@ -249,7 +249,7 @@ tools.build:compiler_executables={"c": "gcc-12", "cpp": "g++-12"}
 
 [`string_view_ret`](#string_view_ret){ #string_view_ret }
 
-:   [:octicons-tag-24: 2.2.0][conan returning string_view] · :octicons-milestone-24: `auto`/`True`/`False` (Default: `auto`)
+:   [:octicons-tag-24: 2.2.0][conan returning string_view] · :octicons-milestone-24: `True`/`False` (Default: automatically determined from settings)
 
     Enables returning `std::string_view` from the
     [`unit_symbol()`](../users_guide/framework_basics/text_output.md#unit_symbol)
@@ -261,7 +261,7 @@ tools.build:compiler_executables={"c": "gcc-12", "cpp": "g++-12"}
 
 [`no_crtp`](#no_crtp){ #no_crtp }
 
-:   [:octicons-tag-24: 2.2.0][conan no crtp support] · :octicons-milestone-24: `auto`/`True`/`False` (Default: `auto`)
+:   [:octicons-tag-24: 2.2.0][conan no crtp support] · :octicons-milestone-24: `True`/`False` (Default: automatically determined from settings)
 
     Removes the need for the usage of the CRTP idiom in the
     [`quantity_spec` definitions](../users_guide/framework_basics/systems_of_quantities.md#defining-quantities).
@@ -342,7 +342,7 @@ tools.build:compiler_executables={"c": "gcc-12", "cpp": "g++-12"}
 
 [`MP_UNITS_API_STD_FORMAT`](#MP_UNITS_API_STD_FORMAT){ #MP_UNITS_API_STD_FORMAT }
 
-:   [:octicons-tag-24: 2.2.0][use fmtlib support] · :octicons-milestone-24: `AUTO`/`TRUE`/`FALSE` (Default: `AUTO`)
+:   [:octicons-tag-24: 2.2.0][use fmtlib support] · :octicons-milestone-24: `ON`/`OFF` (Default: automatically determined)
 
     Enables the usage of [`std::format`](https://en.cppreference.com/w/cpp/utility/format/format)
     and associated facilities for text formatting. If it is not supported, then
@@ -352,7 +352,7 @@ tools.build:compiler_executables={"c": "gcc-12", "cpp": "g++-12"}
 
 [`MP_UNITS_API_STRING_VIEW_RET`](#MP_UNITS_API_STRING_VIEW_RET){ #MP_UNITS_API_STRING_VIEW_RET }
 
-:   [:octicons-tag-24: 2.2.0][cmake returning string_view] · :octicons-milestone-24: `AUTO`/`TRUE`/`FALSE` (Default: `AUTO`)
+:   [:octicons-tag-24: 2.2.0][cmake returning string_view] · :octicons-milestone-24: `ON`/`OFF` (Default: automatically determined)
 
     Enables returning `std::string_view` from the
     [`unit_symbol()`](../users_guide/framework_basics/text_output.md#unit_symbol)
@@ -364,7 +364,7 @@ tools.build:compiler_executables={"c": "gcc-12", "cpp": "g++-12"}
 
 [`MP_UNITS_API_NO_CRTP`](#MP_UNITS_API_NO_CRTP){ #MP_UNITS_API_NO_CRTP }
 
-:   [:octicons-tag-24: 2.2.0][cmake no crtp support] · :octicons-milestone-24: `AUTO`/`TRUE`/`FALSE` (Default: `AUTO`)
+:   [:octicons-tag-24: 2.2.0][cmake no crtp support] · :octicons-milestone-24: `ON`/`OFF` (Default: automatically determined)
 
     Removes the need for the usage of the CRTP idiom in the
     [`quantity_spec` definitions](../users_guide/framework_basics/systems_of_quantities.md#defining-quantities).
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index d51ddfda..b8e4c56f 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -37,48 +37,16 @@ check_libcxx_in_use(${projectPrefix}LIBCXX)
 
 # project build options
 option(${projectPrefix}BUILD_AS_SYSTEM_HEADERS "Exports library as system headers" OFF)
-message(STATUS "${projectPrefix}BUILD_AS_SYSTEM_HEADERS: ${${projectPrefix}BUILD_AS_SYSTEM_HEADERS}")
-
 option(${projectPrefix}BUILD_CXX_MODULES "Add C++ modules to the list of default targets" OFF)
-message(STATUS "${projectPrefix}BUILD_CXX_MODULES: ${${projectPrefix}BUILD_CXX_MODULES}")
 
-option(${projectPrefix}API_FREESTANDING "Builds only freestanding part of the library" OFF)
-message(STATUS "${projectPrefix}API_FREESTANDING: ${${projectPrefix}API_FREESTANDING}")
+message(STATUS "${projectPrefix}BUILD_AS_SYSTEM_HEADERS: ${${projectPrefix}BUILD_AS_SYSTEM_HEADERS}")
+message(STATUS "${projectPrefix}BUILD_CXX_MODULES: ${${projectPrefix}BUILD_CXX_MODULES}")
 
 if(${projectPrefix}BUILD_AS_SYSTEM_HEADERS)
     set(${projectPrefix}_AS_SYSTEM SYSTEM)
 endif()
 
-# project API settings
-function(cache_var_values name)
-    set_property(CACHE ${projectPrefix}${name} PROPERTY STRINGS ${ARGN})
-    if(NOT ${projectPrefix}${name} IN_LIST ARGN)
-        message(FATAL_ERROR
-                    "Invalid value '${${projectPrefix}${name}}' provided for a cache variable ${projectPrefix}${name} (${ARGN} allowed)"
-        )
-    endif()
-    message(STATUS "${projectPrefix}${name}: ${${projectPrefix}${name}}")
-endfunction()
-
-set(${projectPrefix}API_STD_FORMAT AUTO CACHE STRING "Enable `std::format` support")
-cache_var_values(API_STD_FORMAT AUTO TRUE FALSE)
-
-set(${projectPrefix}API_STRING_VIEW_RET AUTO CACHE STRING
-                                                   "Enable returning `std::string_view` from `constexpr` functions"
-)
-cache_var_values(API_STRING_VIEW_RET AUTO TRUE FALSE)
-
-set(${projectPrefix}API_NO_CRTP AUTO CACHE STRING "Enable class definitions without CRTP idiom")
-cache_var_values(API_NO_CRTP AUTO TRUE FALSE)
-
-set(${projectPrefix}API_CONTRACTS GSL-LITE CACHE STRING "Enable contract checking")
-cache_var_values(API_CONTRACTS NONE GSL-LITE MS-GSL)
-
-if(${projectPrefix}API_FREESTANDING AND NOT ${projectPrefix}API_CONTRACTS STREQUAL "NONE")
-    message(FATAL_ERROR "'${projectPrefix}API_CONTRACTS' should be set to 'NONE' for a freestanding build")
-endif()
-
-# C++ features
+# check for C++ features
 check_cxx_feature_supported(__cpp_lib_format ${projectPrefix}LIB_FORMAT_SUPPORTED)
 check_cxx_feature_supported("__cpp_constexpr >= 202211L" ${projectPrefix}STATIC_CONSTEXPR_VARS_IN_CONSTEXPR_FUNCTIONS)
 check_cxx_feature_supported(__cpp_explicit_this_parameter ${projectPrefix}EXPLICIT_THIS_PARAMETER_SUPPORTED)
@@ -91,21 +59,59 @@ if(NOT ${projectPrefix}LIB_FORMAT_SUPPORTED
    AND ${projectPrefix}LIBCXX
 )
     message(STATUS "Clang 17+ with libc++ detected, overriding `std::format` support")
-    set(${projectPrefix}LIB_FORMAT_SUPPORTED 1)
+    set(${projectPrefix}LIB_FORMAT_SUPPORTED ON)
 endif()
 
-# validate settings
-if(NOT ${projectPrefix}API_FREESTANDING AND "${projectPrefix}API_STD_FORMAT" AND NOT
-                                                                                 ${projectPrefix}LIB_FORMAT_SUPPORTED
+# clang++-18 supports explicit `this` parameter
+# https://github.com/llvm/llvm-project/issues/82780
+if(NOT ${projectPrefix}EXPLICIT_THIS_PARAMETER_SUPPORTED
+   AND CMAKE_CXX_COMPILER_ID STREQUAL "Clang"
+   AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL "18")
+    message(STATUS "Clang 18+ detected, overriding `no CRTP` support")
+    set(${projectPrefix}EXPLICIT_THIS_PARAMETER_SUPPORTED ON)
+endif()
+
+# project API settings
+option(${projectPrefix}API_STD_FORMAT "Enable `std::format` support" ${${projectPrefix}LIB_FORMAT_SUPPORTED})
+option(${projectPrefix}API_STRING_VIEW_RET "Enable returning `std::string_view` from `constexpr` functions"
+       ${${projectPrefix}STATIC_CONSTEXPR_VARS_IN_CONSTEXPR_FUNCTIONS}
 )
+option(${projectPrefix}API_NO_CRTP "Enable class definitions without CRTP idiom"
+       ${${projectPrefix}EXPLICIT_THIS_PARAMETER_SUPPORTED}
+)
+option(${projectPrefix}API_FREESTANDING "Builds only freestanding part of the library" OFF)
+set(${projectPrefix}API_CONTRACTS GSL-LITE CACHE STRING "Enable contract checking")
+
+message(STATUS "${projectPrefix}API_STD_FORMAT: ${${projectPrefix}API_STD_FORMAT}")
+message(STATUS "${projectPrefix}API_STRING_VIEW_RET: ${${projectPrefix}API_STRING_VIEW_RET}")
+message(STATUS "${projectPrefix}API_NO_CRTP: ${${projectPrefix}API_NO_CRTP}")
+message(STATUS "${projectPrefix}API_FREESTANDING: ${${projectPrefix}API_FREESTANDING}")
+
+function(cache_var_values name)
+    set_property(CACHE ${projectPrefix}${name} PROPERTY STRINGS ${ARGN})
+    if(NOT ${projectPrefix}${name} IN_LIST ARGN)
+        message(FATAL_ERROR
+                    "Invalid value '${${projectPrefix}${name}}' provided for a cache variable ${projectPrefix}${name} (${ARGN} allowed)"
+        )
+    endif()
+    message(STATUS "${projectPrefix}${name}: ${${projectPrefix}${name}}")
+endfunction()
+cache_var_values(API_CONTRACTS NONE GSL-LITE MS-GSL)
+
+# validate options
+if(${projectPrefix}API_FREESTANDING AND NOT ${projectPrefix}API_CONTRACTS STREQUAL "NONE")
+    message(FATAL_ERROR "'${projectPrefix}API_CONTRACTS' should be set to 'NONE' for a freestanding build")
+endif()
+
+if(NOT ${projectPrefix}API_FREESTANDING AND ${projectPrefix}API_STD_FORMAT AND NOT ${projectPrefix}LIB_FORMAT_SUPPORTED)
     message(FATAL_ERROR "`std::format` enabled but not supported")
 endif()
 
-if("${projectPrefix}API_STRING_VIEW_RET" AND NOT ${projectPrefix}STATIC_CONSTEXPR_VARS_IN_CONSTEXPR_FUNCTIONS)
+if(${projectPrefix}API_STRING_VIEW_RET AND NOT ${projectPrefix}STATIC_CONSTEXPR_VARS_IN_CONSTEXPR_FUNCTIONS)
     message(FATAL_ERROR "`std::string_view` returns enabled but not supported")
 endif()
 
-if("${projectPrefix}API_NO_CRTP" AND NOT ${projectPrefix}EXPLICIT_THIS_PARAMETER_SUPPORTED)
+if(${projectPrefix}API_NO_CRTP AND NOT ${projectPrefix}EXPLICIT_THIS_PARAMETER_SUPPORTED)
     message(FATAL_ERROR "`NO_CRTP` mode enabled but explicit `this` parameter is not supported")
 endif()