diff --git a/lib/libthr/thread/thr_printf.c b/lib/libthr/thread/thr_printf.c
index e1edffe5acb2d4..29c96d6b801879 100644
--- a/lib/libthr/thread/thr_printf.c
+++ b/lib/libthr/thread/thr_printf.c
@@ -58,10 +58,18 @@ _thread_printf(int fd, const char *fmt, ...)
 	va_end(ap);
 }
 
+/* GCC has had this for a long while now, but Clang only got it
+   recently. */
+#if __has_attribute(__nonstring__)
+# define	__nonstring __attribute__((__nonstring__))
+#else
+# define	__nonstring
+#endif
+
 void
 _thread_vprintf(int fd, const char *fmt, va_list ap)
 {
-	static const char digits[16] = "0123456789abcdef";
+	__nonstring static const char digits[16] = "0123456789abcdef";
 	char buf[20];
 	char *s;
 	unsigned long r, u;
diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index d27af520c21d1d..9b0c96fa80dc1d 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -343,12 +343,20 @@ static void (*rtld_exit_ptr)(void);
 			ld_utrace_log(e, h, mb, ms, r, n); \
 	} while (0)
 
+/* GCC has had this for a long while now, but Clang only got it
+   recently. */
+#if __has_attribute(__nonstring__)
+# define	__nonstring __attribute__((__nonstring__))
+#else
+# define	__nonstring
+#endif
+
 static void
 ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
     int refcnt, const char *name)
 {
 	struct utrace_rtld ut;
-	static const char rtld_utrace_sig[RTLD_UTRACE_SIG_SZ] = RTLD_UTRACE_SIG;
+	__nonstring static const char rtld_utrace_sig[RTLD_UTRACE_SIG_SZ] = RTLD_UTRACE_SIG;
 
 	memset(&ut, 0, sizeof(ut));	/* clear holes */
 	memcpy(ut.sig, rtld_utrace_sig, sizeof(ut.sig));