diff --git a/meson.build b/meson.build
index 9bbdb47..74820e6 100644
--- a/meson.build
+++ b/meson.build
@@ -19,9 +19,6 @@ is_mingw = cc.get_id()=='gcc' and host_machine.system()=='windows'
 # Set preprocessor macros
 # Disable .c line numbers in exception tracebacks
 add_project_arguments('-DCYTHON_CLINE_IN_TRACEBACK=0', language: 'c')
-# Disable sanity checking in GNU libc
-# This is required because of false positives in the longjmp() check
-add_project_arguments('-U_FORTIFY_SOURCE', language: 'c')
 
 # Platform-specific settings
 if is_cygwin
diff --git a/src/cysignals/meson.build b/src/cysignals/meson.build
index 062ebfe..1032dd0 100644
--- a/src/cysignals/meson.build
+++ b/src/cysignals/meson.build
@@ -31,6 +31,9 @@ foreach name, pyx : extensions
         cython_args: ['-Wextra'],
         dependencies: [py_dep, threads_dep],
         install: true,
-        subdir: 'cysignals'
+        subdir: 'cysignals',
+        # Disable sanity checking in GNU libc
+        # This is required because of false positives in the longjmp() check
+        c_args: name == 'signals' ? ['-U_FORTIFY_SOURCE'] : [],
     )
 endforeach