diff --git a/stdio-common/bug1.c b/stdio-common/bug1.c
index 18e7d4c257..f23ee5b6bb 100644
--- a/stdio-common/bug1.c
+++ b/stdio-common/bug1.c
@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <libc-diag.h>
 
 int
 main (void)
@@ -13,12 +14,22 @@ main (void)
   stream = open_memstream (&bp, &size);
   fprintf (stream, "hello");
   fflush (stream);
+  /* clang do not handle %Z format.  */
+  DIAG_PUSH_NEEDS_COMMENT_CLANG;
+  DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-invalid-specifier");
+  DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-extra-args");
   printf ("buf = %s, size = %Zu\n", bp, size);
+  DIAG_POP_NEEDS_COMMENT_CLANG;
   lose |= size != 5;
   lose |= strncmp (bp, "hello", size);
   fprintf (stream, ", world");
   fclose (stream);
+  /* clang do not handle %Z format.  */
+  DIAG_PUSH_NEEDS_COMMENT_CLANG;
+  DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-invalid-specifier");
+  DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-extra-args");
   printf ("buf = %s, size = %Zu\n", bp, size);
+  DIAG_POP_NEEDS_COMMENT_CLANG;
   lose |= size != 12;
   lose |= strncmp (bp, "hello, world", 12);
 
diff --git a/stdio-common/bug5.c b/stdio-common/bug5.c
index dfa19aed55..c46810f94c 100644
--- a/stdio-common/bug5.c
+++ b/stdio-common/bug5.c
@@ -6,6 +6,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <libc-diag.h>
 
 #include <support/support.h>
 
@@ -30,7 +31,12 @@ main (void)
       return 1;
     }
   for (i = 0; i < 1000; ++i)
+    /* clang do not handle %Z format.  */
+    DIAG_PUSH_NEEDS_COMMENT_CLANG;
+    DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-invalid-specifier");
+    DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-extra-args");
     fprintf (in, "%Zu\n", i);
+    DIAG_POP_NEEDS_COMMENT_CLANG;
 
   out = fopen (outname, "w");
   if (out == NULL)
diff --git a/stdio-common/test_rdwr.c b/stdio-common/test_rdwr.c
index 67fbe4e1de..8e501ba20f 100644
--- a/stdio-common/test_rdwr.c
+++ b/stdio-common/test_rdwr.c
@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <libc-diag.h>
 
 #include <support/xstdio.h>
 
@@ -54,6 +55,11 @@ main (int argc, char **argv)
   rewind (f);
   (void) fputs (buf, f);
   rewind (f);
+
+  /* clang do not handle %Z format.  */
+  DIAG_PUSH_NEEDS_COMMENT_CLANG;
+  DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-invalid-specifier");
+  DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-extra-args");
   {
     size_t i;
     for (i = 0; i < replace_from; ++i)
@@ -101,6 +107,7 @@ main (int argc, char **argv)
 	lose = 1;
       }
   }
+  DIAG_POP_NEEDS_COMMENT_CLANG;
 
   if (!lose)
     {
diff --git a/stdio-common/tst-fphex.c b/stdio-common/tst-fphex.c
index efba482537..7c0e4bd6fc 100644
--- a/stdio-common/tst-fphex.c
+++ b/stdio-common/tst-fphex.c
@@ -3,6 +3,7 @@
 #include <array_length.h>
 #include <stdio.h>
 #include <string.h>
+#include <libc-diag.h>
 
 #ifndef WIDE
 # define STR_LEN strlen
@@ -56,10 +57,14 @@ do_test (void)
       int n = SPRINT (buf, array_length (buf), t->fmt, t->value);
       if (n != STR_LEN (t->expect) || STR_CMP (buf, t->expect) != 0)
 	{
+	  /* clang do not handle %Z format.  */
+	  DIAG_PUSH_NEEDS_COMMENT_CLANG;
+	  DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat");
 	  PRINT (L_("" S "\tExpected \"" S "\" (%Zu)\n\tGot      \""
 		    S "\" (%d, %Zu)\n"),
 		 t->fmt, t->expect, STR_LEN (t->expect),
 		 buf, n, STR_LEN (buf));
+	  DIAG_POP_NEEDS_COMMENT_CLANG;
 	  result = 1;
 	}
     }
diff --git a/stdio-common/tstgetln.c b/stdio-common/tstgetln.c
index b2e8263283..c0a64d22c7 100644
--- a/stdio-common/tstgetln.c
+++ b/stdio-common/tstgetln.c
@@ -16,6 +16,7 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <stdio.h>
+#include <libc-diag.h>
 
 int
 main (int argc, char *argv[])
@@ -26,7 +27,12 @@ main (int argc, char *argv[])
 
   while ((len = getline (&buf, &size, stdin)) != -1)
     {
+      /* clang do not handle %Z format.  */
+      DIAG_PUSH_NEEDS_COMMENT_CLANG;
+      DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-invalid-specifier");
+      DIAG_IGNORE_NEEDS_COMMENT_CLANG (13, "-Wformat-extra-args");
       printf ("bufsize %Zu; read %Zd: ", size, len);
+      DIAG_POP_NEEDS_COMMENT_CLANG;
       if (fwrite (buf, len, 1, stdout) != 1)
 	{
 	  perror ("fwrite");
