diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index cc59031..8d7085b 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -10,16 +10,14 @@ jobs:
       matrix:
         config:
         # https://github.com/actions/virtual-environments/tree/main/images/linux
-        - { os: "ubuntu-18.04", cc: "gcc-7", cxx: "g++-7" }
-        - { os: "ubuntu-18.04", cc: "gcc-8", cxx: "g++-8" }
-        - { os: "ubuntu-18.04", cc: "gcc-9", cxx: "g++-9" }
-        - { os: "ubuntu-18.04", cc: "gcc-10", cxx: "g++-10" }
-        - { os: "ubuntu-18.04", cc: "clang-5.0", cxx: "clang++-5.0" }
-        - { os: "ubuntu-18.04", cc: "clang-6.0", cxx: "clang++-6.0" }
-        - { os: "ubuntu-18.04", cc: "clang-7", cxx: "clang++-7" }
-        - { os: "ubuntu-18.04", cc: "clang-8", cxx: "clang++-8" }
-        - { os: "ubuntu-18.04", cc: "clang-9", cxx: "clang++-9" }
-        - { os: "ubuntu-18.04", cc: "clang-10", cxx: "clang++-10" }
+        - { os: "ubuntu-20.04", cc: "gcc-7", cxx: "g++-7" }
+        - { os: "ubuntu-20.04", cc: "gcc-8", cxx: "g++-8" }
+        - { os: "ubuntu-20.04", cc: "gcc-9", cxx: "g++-9" }
+        - { os: "ubuntu-20.04", cc: "gcc-10", cxx: "g++-10" }
+        - { os: "ubuntu-20.04", cc: "clang-7", cxx: "clang++-7" }
+        - { os: "ubuntu-20.04", cc: "clang-8", cxx: "clang++-8" }
+        - { os: "ubuntu-20.04", cc: "clang-9", cxx: "clang++-9" }
+        - { os: "ubuntu-20.04", cc: "clang-10", cxx: "clang++-10" }
     name: "${{matrix.config.cxx}}"
     steps:
     - name: Setup
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 388ba98..50cf4a4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,6 +11,17 @@ add_library(${PROJECT_NAME} INTERFACE)
 target_compile_features(${PROJECT_NAME} INTERFACE cxx_std_17)
 target_include_directories(${PROJECT_NAME} INTERFACE headers)
 
+target_compile_options(${PROJECT_NAME}
+    INTERFACE
+    $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>>:
+        -Wno-c++98-compat-pedantic
+        -Wno-covered-switch-default
+        -Wno-ctad-maybe-unsupported
+        -Wno-old-style-cast
+        -Wno-shadow
+        -Wno-unknown-warning-option
+        -Wno-weak-vtables>)
+
 if(BUILD_AS_STANDALONE)
     option(BUILD_WITH_UNTESTS "Build with unit tests" ON)
     if(BUILD_WITH_UNTESTS)
diff --git a/README.md b/README.md
index c167f9d..4f1792d 100644
--- a/README.md
+++ b/README.md
@@ -41,7 +41,7 @@
 ## Requirements
 
 - [gcc](https://www.gnu.org/software/gcc/) **>= 7**
-- [clang](https://clang.llvm.org/) **>= 5.0**
+- [clang](https://clang.llvm.org/) **>= 7**
 - [msvc](https://visualstudio.microsoft.com/) **>= 2017**
 
 ## Installation
diff --git a/headers/enum.hpp/enum.hpp b/headers/enum.hpp/enum.hpp
index d616c18..b1e67cb 100644
--- a/headers/enum.hpp/enum.hpp
+++ b/headers/enum.hpp/enum.hpp
@@ -260,30 +260,28 @@ namespace enum_hpp::detail
             { ENUM_HPP_GENERATE_NAMES(Fields) }\
         };\
     public:\
-        static constexpr underlying_type to_underlying(enum_type e) noexcept {\
+        [[maybe_unused]] static constexpr underlying_type to_underlying(enum_type e) noexcept {\
             return static_cast<underlying_type>(e);\
         }\
-        \
-        static constexpr std::optional<std::string_view> to_string(enum_type e) noexcept {\
+        [[maybe_unused]] static constexpr std::optional<std::string_view> to_string(enum_type e) noexcept {\
             switch ( e ) {\
                 ENUM_HPP_GENERATE_VALUE_TO_NAME_CASES(Enum, Fields)\
                 default: return std::nullopt;\
             }\
         }\
-        static constexpr std::string_view to_string_or_empty(enum_type e) noexcept {\
+        [[maybe_unused]] static constexpr std::string_view to_string_or_empty(enum_type e) noexcept {\
             if ( auto s = to_string(e) ) {\
                 return *s;\
             }\
             return ::enum_hpp::empty_string;\
         }\
-        static std::string_view to_string_or_throw(enum_type e) {\
+        [[maybe_unused]] static std::string_view to_string_or_throw(enum_type e) {\
             if ( auto s = to_string(e) ) {\
                 return *s;\
             }\
             ::enum_hpp::detail::throw_exception_with(#Enum "_traits::to_string_or_throw(): invalid argument");\
         }\
-        \
-        static constexpr std::optional<enum_type> from_string(std::string_view name) noexcept {\
+        [[maybe_unused]] static constexpr std::optional<enum_type> from_string(std::string_view name) noexcept {\
             for ( std::size_t i = 0; i < size; ++i) {\
                 if ( name == names[i] ) {\
                     return values[i];\
@@ -291,52 +289,49 @@ namespace enum_hpp::detail
             }\
             return std::nullopt;\
         }\
-        static constexpr enum_type from_string_or_default(std::string_view name, enum_type def) noexcept {\
+        [[maybe_unused]] static constexpr enum_type from_string_or_default(std::string_view name, enum_type def) noexcept {\
             if ( auto e = from_string(name) ) {\
                 return *e;\
             }\
             return def;\
         }\
-        static enum_type from_string_or_throw(std::string_view name) {\
+        [[maybe_unused]] static enum_type from_string_or_throw(std::string_view name) {\
             if ( auto e = from_string(name) ) {\
                 return *e;\
             }\
             ::enum_hpp::detail::throw_exception_with(#Enum "_traits::from_string_or_throw(): invalid argument");\
         }\
-        \
-        static constexpr std::optional<std::size_t> to_index(enum_type e) noexcept {\
+        [[maybe_unused]] static constexpr std::optional<std::size_t> to_index(enum_type e) noexcept {\
             switch ( e ) {\
                 ENUM_HPP_GENERATE_VALUE_TO_INDEX_CASES(Enum, Fields)\
                 default: return std::nullopt;\
             }\
         }\
-        \
-        static constexpr std::size_t to_index_or_invalid(enum_type e) noexcept {\
+        [[maybe_unused]] static constexpr std::size_t to_index_or_invalid(enum_type e) noexcept {\
             if ( auto i = to_index(e) ) {\
                 return *i;\
             }\
             return ::enum_hpp::invalid_index;\
         }\
-        static std::size_t to_index_or_throw(enum_type e) {\
+        [[maybe_unused]] static std::size_t to_index_or_throw(enum_type e) {\
             if ( auto i = to_index(e) ) {\
                 return *i;\
             }\
             ::enum_hpp::detail::throw_exception_with(#Enum "_traits::to_index_or_throw(): invalid argument");\
         }\
-        \
-        static constexpr std::optional<enum_type> from_index(std::size_t index) noexcept {\
+        [[maybe_unused]] static constexpr std::optional<enum_type> from_index(std::size_t index) noexcept {\
             if ( index < size ) {\
                 return values[index];\
             }\
             return std::nullopt;\
         }\
-        static constexpr enum_type from_index_or_default(std::size_t index, enum_type def) noexcept {\
+        [[maybe_unused]] static constexpr enum_type from_index_or_default(std::size_t index, enum_type def) noexcept {\
             if ( auto e = from_index(index) ) {\
                 return *e;\
             }\
             return def;\
         }\
-        static enum_type from_index_or_throw(std::size_t index) {\
+        [[maybe_unused]] static enum_type from_index_or_throw(std::size_t index) {\
             if ( auto e = from_index(index) ) {\
                 return *e;\
             }\
diff --git a/headers/enum.hpp/enum_bitflags.hpp b/headers/enum.hpp/enum_bitflags.hpp
index a9eccd1..a8645a7 100644
--- a/headers/enum.hpp/enum_bitflags.hpp
+++ b/headers/enum.hpp/enum_bitflags.hpp
@@ -58,7 +58,7 @@ namespace enum_hpp::bitflags
         constexpr bitflags& toggle(bitflags flags) noexcept {
             flags_ ^= flags.flags_;
             return *this;
-        };
+        }
 
         constexpr bitflags& clear(bitflags flags) noexcept {
             flags_ &= ~flags.flags_;
diff --git a/untests/CMakeLists.txt b/untests/CMakeLists.txt
index 5e40ac3..035435b 100644
--- a/untests/CMakeLists.txt
+++ b/untests/CMakeLists.txt
@@ -25,7 +25,10 @@ target_compile_options(${PROJECT_NAME}
     $<$<CXX_COMPILER_ID:MSVC>:
         /WX /W4>
     PRIVATE
-    $<$<OR:$<CXX_COMPILER_ID:GNU>,$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>>:
-        -Werror -Wall -Wextra -Wpedantic>)
+    $<$<CXX_COMPILER_ID:GNU>:
+        -Werror -Wall -Wextra -Wpedantic>
+    PRIVATE
+    $<$<OR:$<CXX_COMPILER_ID:Clang>,$<CXX_COMPILER_ID:AppleClang>>:
+        -Werror -Weverything -Wconversion>)
 
 add_test(${PROJECT_NAME} ${PROJECT_NAME})