Index: src/ctime.c
==================================================================
--- src/ctime.c
+++ src/ctime.c
@@ -58,13 +58,10 @@
   "32BIT_ROWID",
 #endif
 #ifdef SQLITE_4_BYTE_ALIGNED_MALLOC
   "4_BYTE_ALIGNED_MALLOC",
 #endif
-#ifdef SQLITE_64BIT_STATS
-  "64BIT_STATS",
-#endif
 #ifdef SQLITE_ALLOW_COVERING_INDEX_SCAN
 # if SQLITE_ALLOW_COVERING_INDEX_SCAN != 1
   "ALLOW_COVERING_INDEX_SCAN=" CTIMEOPT_VAL(SQLITE_ALLOW_COVERING_INDEX_SCAN),
 # endif
 #endif
@@ -396,10 +393,13 @@
 #ifdef SQLITE_INT64_TYPE
   "INT64_TYPE",
 #endif
 #ifdef SQLITE_INTEGRITY_CHECK_ERROR_MAX
   "INTEGRITY_CHECK_ERROR_MAX=" CTIMEOPT_VAL(SQLITE_INTEGRITY_CHECK_ERROR_MAX),
+#endif
+#ifdef SQLITE_LEGACY_JSON_VALID
+  "LEGACY_JSON_VALID",
 #endif
 #ifdef SQLITE_LIKE_DOESNT_MATCH_BLOBS
   "LIKE_DOESNT_MATCH_BLOBS",
 #endif
 #ifdef SQLITE_LOCK_TRACE

Index: src/json.c
==================================================================
--- src/json.c
+++ src/json.c
@@ -3007,11 +3007,17 @@
   int argc,
   sqlite3_value **argv
 ){
   JsonParse *p;          /* The parse */
   UNUSED_PARAMETER(argc);
-  if( sqlite3_value_type(argv[0])==SQLITE_NULL ) return;
+  if( sqlite3_value_type(argv[0])==SQLITE_NULL ){
+#ifdef SQLITE_LEGACY_JSON_VALID
+    /* Incorrect legacy behavior was to return FALSE for a NULL input */
+    sqlite3_result_int(ctx, 0);
+#endif
+    return;
+  }
   p = jsonParseCached(ctx, argv[0], 0, 0);
   if( p==0 || p->oom ){
     sqlite3_result_error_nomem(ctx);
     sqlite3_free(p);
   }else{

Index: test/json101.test
==================================================================
--- test/json101.test
+++ test/json101.test
@@ -921,13 +921,19 @@
 # 2023-05-02 https://sqlite.org/forum/forumpost/06c6334412
 # JSON functions should normally return NULL when given
 # a NULL value as the JSON input.
 #
 db null NULL
-do_execsql_test json-21.1 {
-  SELECT json_valid(NULL);
-} NULL
+if {[db exists {SELECT * FROM pragma_compile_options WHERE compile_options LIKE '%legacy_json_valid%'}]} {
+  do_execsql_test json-21.1-legacy {
+    SELECT json_valid(NULL);
+  } 0
+} else {
+  do_execsql_test json-21.1-correct {
+    SELECT json_valid(NULL);
+  } NULL
+}
 do_execsql_test json-21.2 {
   SELECT json_error_position(NULL);
 } NULL
 do_execsql_test json-21.3 {
   SELECT json(NULL);

Index: tool/mkctimec.tcl
==================================================================
--- tool/mkctimec.tcl
+++ tool/mkctimec.tcl
@@ -178,10 +178,11 @@
   SQLITE_FTS5_NO_WITHOUT_ROWID
   SQLITE_IGNORE_AFP_LOCK_ERRORS
   SQLITE_IGNORE_FLOCK_LOCK_ERRORS
   SQLITE_INLINE_MEMCPY
   SQLITE_INT64_TYPE
+  SQLITE_LEGACY_JSON_VALID
   SQLITE_LIKE_DOESNT_MATCH_BLOBS
   SQLITE_LOCK_TRACE
   SQLITE_LOG_CACHE_SPILL
   SQLITE_MEMDEBUG
   SQLITE_MIXED_ENDIAN_64BIT_FLOAT