diff --git a/.github/workflows/ubuntu18.yml b/.github/workflows/ubuntu18.yml
index 13b7eee..dbdaa7a 100644
--- a/.github/workflows/ubuntu18.yml
+++ b/.github/workflows/ubuntu18.yml
@@ -9,6 +9,7 @@ jobs:
       fail-fast: false
       matrix:
         include:
+          # Legacy/x86 compilers cause CI failures.
           #- {cxx: -DCMAKE_CXX_COMPILER=g++-5, arch:                         }
           #- {cxx: -DCMAKE_CXX_COMPILER=g++-6, arch:                         }
           - {cxx:                           , arch:                         } # default=gcc7
diff --git a/.github/workflows/ubuntu20.yml b/.github/workflows/ubuntu20.yml
index a0f519f..8fca2d9 100644
--- a/.github/workflows/ubuntu20.yml
+++ b/.github/workflows/ubuntu20.yml
@@ -9,6 +9,7 @@ jobs:
       fail-fast: false
       matrix:
         include:
+          # Legacy/x86 compilers cause CI failures.
           #- {cxx: -DCMAKE_CXX_COMPILER=g++-8, arch:                         }
           - {cxx:                           , arch:                         } # default=gcc9
           #- {cxx:                           , arch: -DCMAKE_CXX_FLAGS="-m32"} # default=gcc9
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 99486dd..d53c92f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,10 +1,17 @@
 cmake_minimum_required(VERSION 3.9)
 
 project(fast_float VERSION 0.7.0 LANGUAGES CXX)
-set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_CXX_STANDARD_REQUIRED OFF)
-
 
+if(FASTFLOAT_TEST)
+  set(CMAKE_CXX_STANDARD 17)
+  set(CMAKE_CXX_STANDARD_REQUIRED OFF)
+  enable_testing()
+  add_subdirectory(tests)
+else(FASTFLOAT_TEST)
+  set(CMAKE_CXX_STANDARD 11)
+  set(CMAKE_CXX_STANDARD_REQUIRED ON)
+  message(STATUS "Tests are disabled. Set FASTFLOAT_TEST to ON to run tests.")
+endif(FASTFLOAT_TEST)
 
 option(FASTFLOAT_SANITIZE "Sanitize addresses" OFF)
 
@@ -28,9 +35,4 @@ if(FASTFLOAT_SANITIZE)
   endif()
 endif()
 
-if(FASTFLOAT_TEST)
-  enable_testing()
-  add_subdirectory(tests)
-else(FASTFLOAT_TEST)
-  message(STATUS "Tests are disabled. Set FASTFLOAT_TEST to ON to run tests.")
-endif(FASTFLOAT_TEST)
+
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 37a659e..713c663 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -38,7 +38,6 @@ function(fast_float_add_cpp_test TEST_NAME)
       target_compile_options(${TEST_NAME} PUBLIC -Wsign-compare -Wshadow -Wwrite-strings -Wpointer-arith -Winit-self -Wconversion -Wsign-conversion)
     endif()
     target_link_libraries(${TEST_NAME} PUBLIC fast_float doctest supplemental-data)
-    target_compile_features(${TEST_NAME} PUBLIC cxx_std_11)
 endfunction(fast_float_add_cpp_test)
 
 
diff --git a/tests/basictest.cpp b/tests/basictest.cpp
index 925b00c..73651bf 100644
--- a/tests/basictest.cpp
+++ b/tests/basictest.cpp
@@ -26,19 +26,21 @@
 #if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__MINGW64__) || defined(sun) || defined(__sun)
 #define FASTFLOAT_ODDPLATFORM 1
 #endif
-
 #if defined __has_include
 #if __has_include (<filesystem>)
 #else
+// filesystem is not available
 #define FASTFLOAT_ODDPLATFORM 1
 #endif
 #else
+// __has_include is not available
 #define FASTFLOAT_ODDPLATFORM 1
 #endif
 
 // C++ 17 because it is otherwise annoying to browse all files in a directory.
 // We also only run these tests on little endian systems.
 #if (FASTFLOAT_CPLUSPLUS >= 201703L) && (FASTFLOAT_IS_BIG_ENDIAN == 0) && !defined(FASTFLOAT_ODDPLATFORM)
+
 #include <iostream>
 #include <filesystem>
 #include <charconv>
@@ -105,7 +107,6 @@ TEST_CASE("supplemental") {
         CHECK(check_file(entry.path().string()));
     }
 }
-
 #endif