diff --git a/config.h.in b/config.h.in
index 92216df4d..8c617c3fd 100644
--- a/config.h.in
+++ b/config.h.in
@@ -1476,10 +1476,17 @@
 #endif
 
 /* For functions that call exit() directly. */
-#if __GNUC_PREREQ__(2, 5)
-# define sudo_noreturn		__attribute__((__noreturn__))
-#else
-# define sudo_noreturn
+#ifdef __has_c_attribute
+# if __has_c_attribute(__noreturn__)
+#  define sudo_noreturn		[[__noreturn__]]
+# endif
+#endif
+#ifndef sudo_noreturn
+# if __GNUC_PREREQ__(2, 5)
+#  define sudo_noreturn		__attribute__((__noreturn__))
+# else
+#  define sudo_noreturn
+# endif
 #endif
 
 /* For malloc-like functions that return uninitialized or zeroed memory. */
@@ -1507,6 +1514,20 @@
 # define sudo_attr_fmt_arg(_f)
 #endif
 
+/* C23 defines a fallthrough attribute, gcc 7.0 and clang 10 have their own. */
+#ifdef __has_c_attribute
+# if __has_c_attribute(__fallthrough__)
+# define FALLTHROUGH		[[__fallthrough__]]
+# endif
+#endif
+#ifndef FALLTHROUGH
+# if defined(HAVE_FALLTHROUGH_ATTRIBUTE)
+#  define FALLTHROUGH		__attribute__((__fallthrough__))
+# else
+#  define FALLTHROUGH		do { } while (0)
+# endif
+#endif
+
 /* Symbol visibility controls. */
 #ifdef HAVE_DSO_VISIBILITY
 # if defined(__GNUC__)
diff --git a/configure.ac b/configure.ac
index 261579bfc..e37fe6027 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5571,10 +5571,17 @@ AH_BOTTOM([#ifndef __GNUC_PREREQ__
 #endif
 
 /* For functions that call exit() directly. */
-#if __GNUC_PREREQ__(2, 5)
-# define sudo_noreturn		__attribute__((__noreturn__))
-#else
-# define sudo_noreturn
+#ifdef __has_c_attribute
+# if __has_c_attribute(__noreturn__)
+#  define sudo_noreturn		[[__noreturn__]]
+# endif
+#endif
+#ifndef sudo_noreturn
+# if __GNUC_PREREQ__(2, 5)
+#  define sudo_noreturn		__attribute__((__noreturn__))
+# else
+#  define sudo_noreturn
+# endif
 #endif
 
 /* For malloc-like functions that return uninitialized or zeroed memory. */
@@ -5602,6 +5609,20 @@ AH_BOTTOM([#ifndef __GNUC_PREREQ__
 # define sudo_attr_fmt_arg(_f)
 #endif
 
+/* C23 defines a fallthrough attribute, gcc 7.0 and clang 10 have their own. */
+#ifdef __has_c_attribute
+# if __has_c_attribute(__fallthrough__)
+# define FALLTHROUGH		[[__fallthrough__]]
+# endif
+#endif
+#ifndef FALLTHROUGH
+# if defined(HAVE_FALLTHROUGH_ATTRIBUTE)
+#  define FALLTHROUGH		__attribute__((__fallthrough__))
+# else
+#  define FALLTHROUGH		do { } while (0)
+# endif
+#endif
+
 /* Symbol visibility controls. */
 #ifdef HAVE_DSO_VISIBILITY
 # if defined(__GNUC__)
diff --git a/include/sudo_compat.h b/include/sudo_compat.h
index 4437a1c3b..edf609ea8 100644
--- a/include/sudo_compat.h
+++ b/include/sudo_compat.h
@@ -37,12 +37,6 @@
  * Macros and functions that may be missing on some operating systems.
  */
 
-#ifdef HAVE_FALLTHROUGH_ATTRIBUTE
-# define FALLTHROUGH 	__attribute__((__fallthrough__))
-#else
-# define FALLTHROUGH 	do { } while (0)
-#endif
-
 /*
  * Given the pointer x to the member m of the struct s, return
  * a pointer to the containing structure.