diff --git a/benchtests/bench-strnlen.c b/benchtests/bench-strnlen.c
index f4904bd0de..2cd561dfd5 100644
--- a/benchtests/bench-strnlen.c
+++ b/benchtests/bench-strnlen.c
@@ -25,6 +25,7 @@
 # define memchr_strnlen wcschr_wcsnlen
 #endif /* WIDE */
 #include "bench-string.h"
+#include "json-lib.h"
 
 #define BIG_CHAR MAX_CHAR
 
@@ -49,15 +50,16 @@ IMPL (memchr_strnlen, 0)
 IMPL (generic_strnlen, 0)
 
 static void
-do_one_test (impl_t *impl, const CHAR *s, size_t maxlen, size_t exp_len)
+do_one_test (json_ctx_t *json_ctx, impl_t *impl, const CHAR *s, size_t maxlen,
+	     size_t exp_len)
 {
   size_t len = CALL (impl, s, maxlen), i, iters = INNER_LOOP_ITERS_LARGE;
   timing_t start, stop, cur;
 
   if (len != exp_len)
     {
-      error (0, 0, "Wrong result in function %s %zd %zd", impl->name,
-	     len, exp_len);
+      error (0, 0, "Wrong result in function %s %zd %zd", impl->name, len,
+	     exp_len);
       ret = 1;
       return;
     }
@@ -71,76 +73,101 @@ do_one_test (impl_t *impl, const CHAR *s, size_t maxlen, size_t exp_len)
 
   TIMING_DIFF (cur, start, stop);
 
-  TIMING_PRINT_MEAN ((double) cur, (double) iters);
+  json_element_double (json_ctx, (double) cur / (double) iters);
 }
 
 static void
-do_test (size_t align, size_t len, size_t maxlen, int max_char)
+do_test (json_ctx_t *json_ctx, size_t align, size_t len, size_t maxlen,
+	 int max_char)
 {
   size_t i;
 
-  align &= 63;
+  align &= getpagesize () - 1;
   if ((align + len) * sizeof (CHAR) >= page_size)
     return;
 
   CHAR *buf = (CHAR *) (buf1);
 
+  json_element_object_begin (json_ctx);
+  json_attr_uint (json_ctx, "len", len);
+  json_attr_uint (json_ctx, "maxlen", maxlen);
+  json_attr_uint (json_ctx, "max_char", max_char);
+  json_attr_uint (json_ctx, "align", align);
+  json_array_begin (json_ctx, "timings");
+
   for (i = 0; i < len; ++i)
     buf[align + i] = 1 + 7 * i % max_char;
   buf[align + len] = 0;
 
-  printf ("Length %4zd, alignment %2zd:", len, align);
-
   FOR_EACH_IMPL (impl, 0)
-    do_one_test (impl, (CHAR *) (buf + align), maxlen, MIN (len, maxlen));
+    do_one_test (json_ctx, impl, (CHAR *) (buf + align), maxlen,
+		 MIN (len, maxlen));
 
-  putchar ('\n');
+  json_array_end (json_ctx);
+  json_element_object_end (json_ctx);
 }
 
 int
 test_main (void)
 {
   size_t i;
+  json_ctx_t json_ctx;
 
   test_init ();
 
-  printf ("%20s", "");
+  json_init (&json_ctx, 0, stdout);
+
+  json_document_begin (&json_ctx);
+  json_attr_string (&json_ctx, "timing_type", TIMING_TYPE);
+
+  json_attr_object_begin (&json_ctx, "functions");
+  json_attr_object_begin (&json_ctx, TEST_NAME);
+  json_attr_string (&json_ctx, "bench-variant", "");
+
+  json_array_begin (&json_ctx, "ifuncs");
   FOR_EACH_IMPL (impl, 0)
-    printf ("\t%s", impl->name);
-  putchar ('\n');
+    json_element_string (&json_ctx, impl->name);
+  json_array_end (&json_ctx);
+
+  json_array_begin (&json_ctx, "results");
 
   for (i = 1; i < 8; ++i)
     {
-      do_test (0, i, i - 1, MIDDLE_CHAR);
-      do_test (0, i, i, MIDDLE_CHAR);
-      do_test (0, i, i + 1, MIDDLE_CHAR);
+      do_test (&json_ctx, 0, i, i - 1, MIDDLE_CHAR);
+      do_test (&json_ctx, 0, i, i, MIDDLE_CHAR);
+      do_test (&json_ctx, 0, i, i + 1, MIDDLE_CHAR);
     }
 
   for (i = 1; i < 8; ++i)
     {
-      do_test (i, i, i - 1, MIDDLE_CHAR);
-      do_test (i, i, i, MIDDLE_CHAR);
-      do_test (i, i, i + 1, MIDDLE_CHAR);
+      do_test (&json_ctx, i, i, i - 1, MIDDLE_CHAR);
+      do_test (&json_ctx, i, i, i, MIDDLE_CHAR);
+      do_test (&json_ctx, i, i, i + 1, MIDDLE_CHAR);
     }
 
   for (i = 2; i <= 10; ++i)
     {
-      do_test (0, 1 << i, 5000, MIDDLE_CHAR);
-      do_test (1, 1 << i, 5000, MIDDLE_CHAR);
+      do_test (&json_ctx, 0, 1 << i, 5000, MIDDLE_CHAR);
+      do_test (&json_ctx, 1, 1 << i, 5000, MIDDLE_CHAR);
     }
 
   for (i = 1; i < 8; ++i)
-    do_test (0, i, 5000, BIG_CHAR);
+    do_test (&json_ctx, 0, i, 5000, BIG_CHAR);
 
   for (i = 1; i < 8; ++i)
-    do_test (i, i, 5000, BIG_CHAR);
+    do_test (&json_ctx, i, i, 5000, BIG_CHAR);
 
   for (i = 2; i <= 10; ++i)
     {
-      do_test (0, 1 << i, 5000, BIG_CHAR);
-      do_test (1, 1 << i, 5000, BIG_CHAR);
+      do_test (&json_ctx, 0, 1 << i, 5000, BIG_CHAR);
+      do_test (&json_ctx, 1, 1 << i, 5000, BIG_CHAR);
     }
 
+  json_array_end (&json_ctx);
+  json_attr_object_end (&json_ctx);
+  json_attr_object_end (&json_ctx);
+  json_document_end (&json_ctx);
+
   return ret;
 }