diff -up diffutils-3.7/lib/c-stack.c.sigstksz diffutils-3.7/lib/c-stack.c
--- diffutils-3.7/lib/c-stack.c.sigstksz	2021-04-12 10:58:48.892279388 +0100
+++ diffutils-3.7/lib/c-stack.c	2021-04-12 11:04:59.488695551 +0100
@@ -52,12 +52,18 @@ typedef struct sigaltstack stack_t;
 #endif
 #ifndef SIGSTKSZ
 # define SIGSTKSZ 16384
-#elif HAVE_LIBSIGSEGV && SIGSTKSZ < 16384
+#elif HAVE_LIBSIGSEGV
 /* libsigsegv 2.6 through 2.8 have a bug where some architectures use
    more than the Linux default of an 8k alternate stack when deciding
    if a fault was caused by stack overflow.  */
-# undef SIGSTKSZ
-# define SIGSTKSZ 16384
+# if defined _SC_SIGSTKSZ && _SC_SIGSTKSZ < 16384
+   /* glibc 2.34 defines SIGSTKSZ to sysconf (_SC_SIGSTKSZ) */
+#  undef SIGSTKSZ
+#  define SIGSTKSZ 16384
+# elif SIGSTKSZ < 16384
+#  undef SIGSTKSZ
+#  define SIGSTKSZ 16384
+# endif
 #endif
 
 #include <stdlib.h>