diff --git a/configure.ac b/configure.ac
index b4a9b30691..2dba99838f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2982,6 +2982,10 @@ AC_DEFUN
   if test "${HAVE_JSON}" = yes; then
     AC_DEFINE(HAVE_JSON, 1, [Define if using Jansson.])
     JSON_OBJ=json.o
+    OLDLIBS="$LIBS"
+    LIBS="$LIBS $JSON_LIBS"
+    AC_CHECK_FUNCS(json_dumpb)
+    LIBS="$OLDLIBS"
   fi
 
   # Windows loads libjansson dynamically
diff --git a/src/json.c b/src/json.c
index 928825e034..361581c2f4 100644
--- a/src/json.c
+++ b/src/json.c
@@ -31,7 +31,7 @@ along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.  */
 #include "coding.h"
 
 #define JSON_HAS_ERROR_CODE (JANSSON_VERSION_HEX >= 0x020B00)
-
+#undef HAVE_JSON_DUMPB
 #ifdef WINDOWSNT
 # include <windows.h>
 # include "w32common.h"
@@ -53,6 +53,11 @@ DEF_DLL_FN (json_t *, json_integer, (json_int_t value));
 DEF_DLL_FN (json_t *, json_real, (double value));
 DEF_DLL_FN (json_t *, json_stringn, (const char *value, size_t len));
 DEF_DLL_FN (char *, json_dumps, (const json_t *json, size_t flags));
+# ifdef HAVE_JSON_DUMPB
+DEF_DLL_FN (void, json_dumpb, (const json_t *json, char *buffer,
+                               size_t size,
+                               size_t flags));
+# endif
 DEF_DLL_FN (int, json_dump_callback,
 	    (const json_t *json, json_dump_callback_t callback, void *data,
 	     size_t flags));
@@ -104,6 +109,9 @@ init_json_functions (void)
   LOAD_DLL_FN (library, json_real);
   LOAD_DLL_FN (library, json_stringn);
   LOAD_DLL_FN (library, json_dumps);
+# ifdef HAVE_JSON_DUMPB
+  LOAD_DLL_FN (library, json_dumpb);
+# endif
   LOAD_DLL_FN (library, json_dump_callback);
   LOAD_DLL_FN (library, json_integer_value);
   LOAD_DLL_FN (library, json_real_value);
@@ -605,6 +613,10 @@ usage: (json-serialize OBJECT &rest ARGS)  */)
 {
   ptrdiff_t count = SPECPDL_INDEX ();
 
+#ifdef HAVE_JSON_DUMPB
+  USE_SAFE_ALLOCA;
+#endif
+
 #ifdef WINDOWSNT
   if (!json_initialized)
     {
@@ -625,16 +637,34 @@ usage: (json-serialize OBJECT &rest ARGS)  */)
   json_parse_args (nargs - 1, args + 1, &conf, false);
 
   json_t *json = lisp_to_json_toplevel (args[0], &conf);
-  record_unwind_protect_ptr (json_release_object, json);
 
+#ifdef HAVE_JSON_DUMPB
+  /* Called with NULL to determine the size of buffer needed.  */
+  size_t size = json_dumpb (json, NULL, 0, 0);
+  char *string = SAFE_ALLOCA (size);
+
+  size = json_dumpb (json, string, size, JSON_COMPACT);
+
+  json_release_object (json);
+
+  if (!size)
+    json_out_of_memory ();
+
+
+  return SAFE_FREE_UNBIND_TO (count, json_make_string (string, size));
+#else
   /* If desired, we might want to add the following flags:
      JSON_DECODE_ANY, JSON_ALLOW_NUL.  */
   char *string = json_dumps (json, JSON_COMPACT);
+
+  json_release_object (json);
+
   if (string == NULL)
     json_out_of_memory ();
   record_unwind_protect_ptr (json_free, string);
 
   return unbind_to (count, json_build_string (string));
+#endif
 }
 
 struct json_buffer_and_size