diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 879e6435..d29e522e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -40,14 +40,6 @@ jobs:
           - os: "windows-2022"
             compiler: "msvc"
             vcvarsall: false
-          - os: "macos-11"
-            compiler: "gcc"
-            cmake: true
-            vcvarsall: true
-          - os: "macos-13"
-            compiler: "gcc"
-            cmake: true
-            vcvarsall: true
         exclude:
           # fails with an internal error
           - os: "macos-12"
diff --git a/src/Hardening.cmake b/src/Hardening.cmake
index eb8c985d..dc7bb670 100644
--- a/src/Hardening.cmake
+++ b/src/Hardening.cmake
@@ -44,7 +44,7 @@ function(
         list(APPEND HARDENING_COMPILE_OPTIONS -Wstringop-overflow=4 -Wformat-overflow=2)
       endif()
 
-      target_compile_definitions(${_project_name} INTERFACE $<$<CONFIG:Release,RelWithDebInfo>:_FORTIFY_SOURCE=3>)
+      target_compile_options(${_project_name} INTERFACE $<$<CONFIG:Release,RelWithDebInfo>:-U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3>)
     endif()
 
     if(${ENABLE_ELF_PROTECTION})
diff --git a/tests/myproj/CMakeLists.txt b/tests/myproj/CMakeLists.txt
index d578b17f..1bfa2849 100644
--- a/tests/myproj/CMakeLists.txt
+++ b/tests/myproj/CMakeLists.txt
@@ -88,6 +88,10 @@ project_options(
   # CLANG_WARNINGS "-Weverything"
   LINKER
   "${LINKER}"
+
+  # Test if _FORTIFY_SOURCE is defined only once when ENABLE_OVERFLOW_PROTECTION
+  ENABLE_OVERFLOW_PROTECTION
+  CLANG_TIDY_EXTRA_ARGUMENTS "-warnings-as-errors=clang-diagnostic-macro-redefined"
 )
 # NOTE: project_options and project_warnings are defined inside project_options