diff --git a/manifest b/manifest
index f1e356acec..011acb7799 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sa\spotential\suse\sof\suninitialized\svalue\sin\sjson_valid()\swith\s2nd\nargument\sof\s8.
-D 2023-12-11T02:39:11.053
+C The\sjson_valid(*,8)\sfunction\sdoes\sa\smuch\sbetter\scheck\sof\sthe\svalidity\sof\nthe\sJSONB\sinput.\s\sThe\sjson_error_position()\sfunction\sreturns\san\sapproximate\nbyte\soffset\sto\sthe\spoint\sof\sthe\sfirst\sdetected\serror\sin\sthe\sJSONB.
+D 2023-12-12T17:31:17.429
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -690,16 +690,16 @@ F src/expr.c 05278def9c186b5875d6903ea26148c7461b9ce0344f0fd7be9a0dfea0a4538a
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c a47610f0a5c6cb0ad79f8fcef039c01833dec0c751bb695f28dc0ec6a4c3ba00
 F src/func.c 472f6dcfa39cf54f89a6aec76c79c225fb880a6c14469c15d361331662b9bf43
-F src/global.c 29f56a330ed9d1b5cd9b79ac0ca36f97ac3afc730ff8bfa987b0db9e559d684d
+F src/global.c 765a0656d6cbf043cb272ff0ae38f39cc46713539ffe6793258ed3eb4b188b52
 F src/hash.c 9ee4269fb1d6632a6fecfb9479c93a1f29271bddbbaf215dd60420bcb80c7220
 F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
 F src/hwtime.h f9c2dfb84dce7acf95ce6d289e46f5f9d3d1afd328e53da8f8e9008e3b3caae6
 F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c 3f0a94082d978bbdd33c38fefea15346c6c6bffb70bc645a71dc0f1f87dd3276
-F src/json.c 022548736478f10bec4f2766f2c9fe1cc25c06b14cabb0ca64b4a1beb83fbf16
+F src/json.c cd270629b4b99d065522b45c3d2b5185491b1ab3544843c6f780aa50755d54dc
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 7432c944ff197046d67a1207790a1b13eec4548c85a9457eb0896bb3641dfb36
-F src/main.c 1b89f3de98d1b59fec5bac1d66d6ece21f703821b8eaa0d53d9604c35309f6f9
+F src/main.c ce714ee501122c76eb2e69b292bebe443aba611fc3b88e6786eb910285515fe4
 F src/malloc.c f016922435dc7d1f1f5083a03338a3e91f8c67ce2c5bdcfa4cdef62e612f5fcc
 F src/mem0.c 6a55ebe57c46ca1a7d98da93aaa07f99f1059645
 F src/mem1.c 3bb59158c38e05f6270e761a9f435bf19827a264c13d1631c58b84bdc96d73b2
@@ -737,11 +737,11 @@ F src/random.c 606b00941a1d7dd09c381d3279a058d771f406c5213c9932bbd93d5587be4b9c
 F src/resolve.c d017bad7ba8e778617701a0e986fdeb393d67d6afa84fb28ef4e8b8ad2acf916
 F src/rowset.c 8432130e6c344b3401a8874c3cb49fefe6873fec593294de077afea2dce5ec97
 F src/select.c 9f55c9f3307b9888f62abe709eec245e98ff217bd14c044f93d72810bb7dc445
-F src/shell.c.in 9b6c3e641de45651ad0b5e9c26cd2f72efabee28179a5315d15c54239515ee3a
-F src/sqlite.h.in d93a4821d2f792467a60f7dc81268d1bb8634f40c31694ef254cab4f9921f96a
+F src/shell.c.in 0cd2ef4b3c814dded5436625ab664d9a973cbc4266a1768e3aa4cbf11bb41eca
+F src/sqlite.h.in adcc7dbfeea1e69d6d487139a7e90db8a48fe998f3f5bb0f85c683e6a6fa68ca
 F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
 F src/sqlite3ext.h 3f046c04ea3595d6bfda99b781926b17e672fd6d27da2ba6d8d8fc39981dcb54
-F src/sqliteInt.h 39b6fe0652c763d8ff6bd0a2427c009e5abe05fb70f5a0cb145a34bcc614fb90
+F src/sqliteInt.h 615524fff083abf9353aa4a3a8adca2d32b3e61e014e62b1a5335c454a386783
 F src/sqliteLimit.h 33b1c9baba578d34efe7dfdb43193b366111cdf41476b1e82699e14c11ee1fb6
 F src/status.c 160c445d7d28c984a0eae38c144f6419311ed3eace59b44ac6dafc20db4af749
 F src/table.c 0f141b58a16de7e2fbe81c308379e7279f4c6b50eb08efeec5892794a0ba30d1
@@ -1229,7 +1229,7 @@ F test/fuzz3.test 9c813e6613b837cb7a277b0383cd66bfa07042b4cf0317157c35852f30043c
 F test/fuzz4.test c229bcdb45518a89e1d208a21343e061503460ac69fae1539320a89f572eb634
 F test/fuzz_common.tcl b7197de6ed1ee8250a4f82d67876f4561b42ee8cbbfc6160dcb66331bad3f830
 F test/fuzz_malloc.test f348276e732e814802e39f042b1f6da6362a610af73a528d8f76898fde6b22f2
-F test/fuzzcheck.c 69b8549e112fb815931a8c14c7955a0c407ae91a79356eecb82458384f2cb989
+F test/fuzzcheck.c 442b0b02146bb905c47c4ee1388949e7fd9d27acf22d9535e9abf216e582b956
 F test/fuzzdata1.db 3e86d9cf5aea68ddb8e27c02d7dfdaa226347426c7eb814918e4d95475bf8517
 F test/fuzzdata2.db 128b3feeb78918d075c9b14b48610145a0dd4c8d6f1ca7c2870c7e425f5bf31f
 F test/fuzzdata3.db c6586d3e3cef0fbc18108f9bb649aa77bfc38aba
@@ -2153,8 +2153,9 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 1503cba6d17e9bade7a5c103ddd23241ff4741f9a2e3032ffe2987af243dae65
-R 10c5202c73d5a29cc977b618b1930c91
+P fa102036fe46eeb71b7df3e265be1935ae5c78e0b939b08841bcfb8abadbc77a c96ebb086feb89341565cc52b970ae7799ce1327fe1ad4fc790f1b0dcaa6e229
+R 6e221a94cd5525fe9f8a7e94ea467b60
+T +closed c96ebb086feb89341565cc52b970ae7799ce1327fe1ad4fc790f1b0dcaa6e229
 U drh
-Z 03628577bea44fb563932e72818a5e19
+Z 749a6c45182c15aa056f901d03cf2368
 # Remove this line to create a well-formed Fossil manifest.
diff --git a/manifest.uuid b/manifest.uuid
index c4f83fcd22..5e0946fbbd 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-fa102036fe46eeb71b7df3e265be1935ae5c78e0b939b08841bcfb8abadbc77a
\ No newline at end of file
+840efb33a3934a9bdccad65ea15c70d5c335a517502c9844aaad8405d16d1604
\ No newline at end of file
diff --git a/src/global.c b/src/global.c
index 60cd13e2ab..7f27d91d15 100644
--- a/src/global.c
+++ b/src/global.c
@@ -244,6 +244,9 @@ SQLITE_WSD struct Sqlite3Config sqlite3Config = {
    0,                         /* bSmallMalloc */
    1,                         /* bExtraSchemaChecks */
    sizeof(LONGDOUBLE_TYPE)>8, /* bUseLongDouble */
+#ifdef SQLITE_DEBUG
+   0,                         /* bJsonSelfcheck */
+#endif
    0x7ffffffe,                /* mxStrlen */
    0,                         /* neverCorrupt */
    SQLITE_DEFAULT_LOOKASIDE,  /* szLookaside, nLookaside */
diff --git a/src/json.c b/src/json.c
index 71a1b789a4..e94cac6d52 100644
--- a/src/json.c
+++ b/src/json.c
@@ -176,7 +176,9 @@ static const char jsonSpaces[] = "\011\012\015\040";
 
 /*
 ** Characters that are special to JSON.  Control characters,
-** '"' and '\\'.
+** '"' and '\\' and '\''.  Actually, '\'' is not special to
+** canonical JSON, but it is special in JSON-5, so we include
+** it in the set of special characters.
 */
 static const char jsonIsOk[256] = {
   0, 0, 0, 0, 0, 0, 0, 0,  0, 0, 0, 0, 0, 0, 0, 0,
@@ -336,6 +338,8 @@ static u32 jsonXlateBlobToText(const JsonParse*,u32,JsonString*);
 static void jsonReturnParse(sqlite3_context*,JsonParse*);
 static JsonParse *jsonParseFuncArg(sqlite3_context*,sqlite3_value*,u32);
 static void jsonParseFree(JsonParse*);
+static u32 jsonbPayloadSize(const JsonParse*, u32, u32*);
+static u32 jsonUnescapeOneChar(const char*, u32, u32*);
 
 /**************************************************************************
 ** Utility routines for dealing with JsonCache objects
@@ -1228,6 +1232,208 @@ static int jsonIs4HexB(const char *z, int *pOp){
   return 1;
 }
 
+
+/*
+** Check a single element of the JSONB in pParse for validity.
+**
+** The element to be checked starts at offset i and must end at on the
+** last byte before iEnd.
+**
+** Return 0 if everything is correct.  Return the 1-based byte offset of the
+** error if a problem is detected.  (In other words, if the error is at offset
+** 0, return 1).
+*/
+static u32 jsonbValidityCheck(
+  const JsonParse *pParse,    /* Input JSONB.  Only aBlob and nBlob are used */
+  u32 i,                      /* Start of element as pParse->aBlob[i] */
+  u32 iEnd,                   /* One more than the last byte of the element */
+  u32 iDepth                  /* Current nesting depth */
+){
+  u32 n, sz, j, k;
+  const u8 *z;
+  u8 x;
+  if( iDepth>JSON_MAX_DEPTH ) return i+1;
+  sz = 0;
+  n = jsonbPayloadSize(pParse, i, &sz);
+  if( NEVER(n==0) ) return i+1;          /* Checked by caller */
+  if( NEVER(i+n+sz!=iEnd) ) return i+1;  /* Checked by caller */
+  z = pParse->aBlob;
+  x = z[i] & 0x0f;
+  switch( x ){
+    case JSONB_NULL:
+    case JSONB_TRUE:
+    case JSONB_FALSE: {
+      return n+sz==1 ? 0 : i+1;
+    }
+    case JSONB_INT: {
+      if( sz<1 ) return i+1;
+      j = i+n;
+      if( z[j]=='-' ){
+        j++;
+        if( sz<2 ) return i+1;
+      }
+      k = i+n+sz;
+      while( j<k ){
+        if( sqlite3Isdigit(z[j]) ){
+          j++;
+        }else{
+          return j+1;
+        }
+      }
+      return 0;
+    }
+    case JSONB_INT5: {
+      if( sz<3 ) return i+1;
+      j = i+n;
+      if( z[j]=='-' ){
+        if( sz<4 ) return i+1;
+        j++;
+      }
+      if( z[j]!='0' ) return i+1;
+      if( z[j+1]!='x' && z[j+1]!='X' ) return j+2;
+      j += 2;
+      k = i+n+sz;
+      while( j<k ){
+        if( sqlite3Isxdigit(z[j]) ){
+          j++;
+        }else{
+          return j+1;
+        }
+      }
+      return 0;
+    }
+    case JSONB_FLOAT:
+    case JSONB_FLOAT5: {
+      u8 seen = 0;   /* 0: initial.  1: '.' seen  2: 'e' seen */
+      if( sz<2 ) return i+1;
+      j = i+n;
+      k = j+sz;
+      if( z[j]=='-' ){
+        j++;
+        if( sz<3 ) return i+1;
+      }
+      if( z[j]=='.' ){
+        if( x==JSONB_FLOAT ) return j+1;
+        if( !sqlite3Isdigit(z[j+1]) ) return j+1;
+        j += 2;
+        seen = 1;
+      }else if( z[j]=='0' && x==JSONB_FLOAT ){
+        if( j+3>k ) return j+1;
+        if( z[j+1]!='.' && z[j+1]!='e' && z[j+1]!='E' ) return j+1;
+        j++;
+      }
+      for(; j<k; j++){
+        if( sqlite3Isdigit(z[j]) ) continue;
+        if( z[j]=='.' ){
+          if( seen>0 ) return j+1;
+          if( x==JSONB_FLOAT && (j==k-1 || !sqlite3Isdigit(z[j+1])) ){
+            return j+1;
+          }
+          seen = 1;
+          continue;
+        }
+        if( z[j]=='e' || z[j]=='E' ){
+          if( seen==2 ) return j+1;
+          if( j==k-1 ) return j+1;
+          if( z[j+1]=='+' || z[j+1]=='-' ){
+            j++;
+            if( j==k-1 ) return j+1;
+          }
+          seen = 2;
+          continue;
+        }
+        return j+1;
+      }
+      if( seen==0 ) return i+1;
+      return 0;
+    }
+    case JSONB_TEXT: {
+      j = i+n;
+      k = j+sz;
+      while( j<k ){
+        if( !jsonIsOk[z[j]] && z[j]!='\'' ) return j+1;
+        j++;
+      }
+      return 0;
+    }
+    case JSONB_TEXTJ:
+    case JSONB_TEXT5: {
+      j = i+n;
+      k = j+sz;
+      while( j<k ){
+        if( !jsonIsOk[z[j]] && z[j]!='\'' ){
+          if( z[j]=='"' ){
+            if( x==JSONB_TEXTJ ) return j+1;
+            j++;
+          }else if( z[j]!='\\' || j+1>=k ){
+            return j+1;
+          }else if( strchr("\"\\/bfnrt",z[j+1])!=0 ){
+            j++;
+          }else if( z[j+1]=='u' ){
+            if( j+5>=k ) return j+1;
+            if( !jsonIs4Hex((const char*)&z[j+2]) ) return j+1;
+            j++;
+          }else if( x!=JSONB_TEXT5 ){
+            return j+1;
+          }else{
+            u32 c = 0;
+            u32 szC = jsonUnescapeOneChar((const char*)&z[j], k-j, &c);
+            if( c==0xfffd ) return j+1;
+            j += szC - 1;
+          }
+        }
+        j++;
+      }
+      return 0;
+    }
+    case JSONB_TEXTRAW: {
+      return 0;
+    }
+    case JSONB_ARRAY: {
+      u32 sub;
+      j = i+n;
+      k = j+sz;
+      while( j<k ){
+        sz = 0;
+        n = jsonbPayloadSize(pParse, j, &sz);
+        if( n==0 ) return j+1;
+        if( j+n+sz>k ) return j+1;
+        sub = jsonbValidityCheck(pParse, j, j+n+sz, iDepth+1);
+        if( sub ) return sub;
+        j += n + sz;
+      }
+      assert( j==k );
+      return 0;
+    }
+    case JSONB_OBJECT: {
+      u32 cnt = 0;
+      u32 sub;
+      j = i+n;
+      k = j+sz;
+      while( j<k ){
+        sz = 0;
+        n = jsonbPayloadSize(pParse, j, &sz);
+        if( n==0 ) return j+1;
+        if( j+n+sz>k ) return j+1;
+        if( (cnt & 1)==0 ){
+          x = z[j] & 0x0f;
+          if( x<JSONB_TEXT || x>JSONB_TEXTRAW ) return j+1;
+        }
+        sub = jsonbValidityCheck(pParse, j, j+n+sz, iDepth+1);
+        if( sub ) return sub;
+        cnt++;
+        j += n + sz;
+      }
+      assert( j==k );
+      if( (cnt & 1)!=0 ) return j+1;
+      return 0;
+    }
+    default: {
+      return i+1;
+    }
+  }
+}
+
 /*
 ** Translate a single element of JSON text at pParse->zJson[i] into
 ** its equivalent binary JSONB representation.  Append the translation into
@@ -1456,6 +1662,8 @@ json_parse_restart:
         /* Control characters are not allowed in strings */
         pParse->iErr = j;
         return -1;
+      }else if( c=='"' ){
+        opcode = JSONB_TEXT5;
       }
       j++;
     }
@@ -1713,7 +1921,12 @@ static int jsonConvertTextToBlob(
   i = jsonXlateTextToBlob(pParse, 0);
   if( pParse->oom ) i = -1;
   if( i>0 ){
+#ifdef SQLITE_DEBUG
     assert( pParse->iDepth==0 );
+    if( sqlite3Config.bJsonSelfcheck ){
+      assert( jsonbValidityCheck(pParse, 0, pParse->nBlob, 0)==0 );
+    }   
+#endif
     while( jsonIsspace(zJson[i]) ) i++;
     if( zJson[i] ){
       i += json5Whitespace(&zJson[i]);
@@ -1910,13 +2123,13 @@ static u32 jsonXlateBlobToText(
       }
       break;
     }
+    case JSONB_TEXT:
     case JSONB_TEXTJ: {
       jsonAppendChar(pOut, '"');
       jsonAppendRaw(pOut, (const char*)&pParse->aBlob[i+n], sz);
       jsonAppendChar(pOut, '"');
       break;
     }
-    case JSONB_TEXT:
     case JSONB_TEXT5: {
       const char *zIn;
       u32 k;
@@ -3954,38 +4167,19 @@ static void jsonValidFunc(
     case SQLITE_BLOB: {
       if( (flags & 0x0c)!=0 && jsonFuncArgMightBeBinary(argv[0]) ){
         if( flags & 0x04 ){
-          /* Superficial checking only - accomplisehd by the
+          /* Superficial checking only - accomplished by the
           ** jsonFuncArgMightBeBinary() call above. */
           res = 1;
         }else{
           /* Strict checking.  Check by translating BLOB->TEXT->BLOB.  If
           ** no errors occur, call that a "strict check". */
           JsonParse px;
-          JsonString sx;
-          u8 oom = 0;
+          u32 iErr;
           memset(&px, 0, sizeof(px));
           px.aBlob = (u8*)sqlite3_value_blob(argv[0]);
           px.nBlob = sqlite3_value_bytes(argv[0]);
-          jsonStringInit(&sx, 0);
-          jsonXlateBlobToText(&px, 0, &sx);
-          jsonParseReset(&px);
-          if( sx.eErr & JSTRING_OOM ) oom = 1;
-          if( sx.eErr==0 ){
-            memset(&px, 0, sizeof(px));
-            jsonStringTerminate(&sx);
-            px.zJson = sx.zBuf;
-            px.nJson = sx.nUsed;
-            if( jsonXlateTextToBlob(&px, 0)==px.nJson ){
-              res = 1;
-            }
-            oom |= px.oom;
-            jsonParseReset(&px);
-          }
-          jsonStringReset(&sx);
-          if( oom ){
-            sqlite3_result_error_nomem(ctx);
-            return;
-          }
+          iErr = jsonbValidityCheck(&px, 0, px.nBlob, 1);
+          res = iErr==0;
         }
       }
       break;
@@ -4019,9 +4213,9 @@ static void jsonValidFunc(
 **
 ** If the argument is NULL, return NULL
 **
-** If the argument is BLOB, do a fast validity check and return non-zero
-** if the check fails.  The returned value does not indicate where in the
-** BLOB the error occurs.
+** If the argument is BLOB, do a full validity check and return non-zero
+** if the check fails.  The return value is the approximate 1-based offset
+** to the byte of the element that contains the first error.
 **
 ** Otherwise interpret the argument is TEXT (even if it is numeric) and
 ** return the 1-based character position for where the parser first recognized
@@ -4040,15 +4234,9 @@ static void jsonErrorFunc(
   UNUSED_PARAMETER(argc);
   memset(&s, 0, sizeof(s));
   if( jsonFuncArgMightBeBinary(argv[0]) ){
-    JsonString out;
-    jsonStringInit(&out, 0);
     s.aBlob = (u8*)sqlite3_value_blob(argv[0]);
     s.nBlob = sqlite3_value_bytes(argv[0]);
-    jsonXlateBlobToText(&s, 0, &out);
-    if( out.eErr ){
-      iErrPos = (out.eErr & JSTRING_MALFORMED)!=0 ? 1 : -1;
-    }
-    jsonStringReset(&out);
+    iErrPos = (i64)jsonbValidityCheck(&s, 0, s.nBlob, 1);
   }else{
     s.zJson = (char*)sqlite3_value_text(argv[0]);
     if( s.zJson==0 ) return;  /* NULL input or OOM */
diff --git a/src/main.c b/src/main.c
index 6acfdc325d..50572ef87f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -4659,6 +4659,28 @@ int sqlite3_test_control(int op, ...){
       break;
     }
 #endif
+
+    /* sqlite3_test_control(SQLITE_TESTCTRL_JSON_SELFCHECK, &onOff);
+    **
+    ** Activate or deactivate validation of JSONB that is generated from
+    ** text.  Off by default, as the validation is slow.  Validation is
+    ** only available if compiled using SQLITE_DEBUG.
+    **
+    ** If onOff is initially 1, then turn it on.  If onOff is initially
+    ** off, turn it off.  If onOff is initially -1, then change onOff
+    ** to be the current setting.
+    */
+    case SQLITE_TESTCTRL_JSON_SELFCHECK: {
+#if defined(SQLITE_DEBUG)
+      int *pOnOff = va_arg(ap, int*);
+      if( *pOnOff<0 ){
+        *pOnOff = sqlite3Config.bJsonSelfcheck;
+      }else{
+        sqlite3Config.bJsonSelfcheck = (u8)((*pOnOff)&0xff);
+      }
+#endif
+      break;
+    }
   }
   va_end(ap);
 #endif /* SQLITE_UNTESTABLE */
diff --git a/src/shell.c.in b/src/shell.c.in
index 6d1312d0f8..35ed0cb5c4 100644
--- a/src/shell.c.in
+++ b/src/shell.c.in
@@ -10756,6 +10756,7 @@ static int do_meta_command(char *zLine, ShellState *p){
     {"fk_no_action",       SQLITE_TESTCTRL_FK_NO_ACTION, 0, "BOOLEAN"       },
     {"imposter",         SQLITE_TESTCTRL_IMPOSTER,1,"SCHEMA ON/OFF ROOTPAGE"},
     {"internal_functions", SQLITE_TESTCTRL_INTERNAL_FUNCTIONS,0,""          },
+    {"json_selfcheck",     SQLITE_TESTCTRL_JSON_SELFCHECK ,0,"BOOLEAN"      },
     {"localtime_fault",    SQLITE_TESTCTRL_LOCALTIME_FAULT,0,"BOOLEAN"      },
     {"never_corrupt",      SQLITE_TESTCTRL_NEVER_CORRUPT,1, "BOOLEAN"       },
     {"optimizations",      SQLITE_TESTCTRL_OPTIMIZATIONS,0,"DISABLE-MASK"   },
@@ -10974,6 +10975,16 @@ static int do_meta_command(char *zLine, ShellState *p){
             isOk = 3;
           }
           break;
+        case SQLITE_TESTCTRL_JSON_SELFCHECK:
+          if( nArg==2 ){
+            rc2 = -1;
+            isOk = 1;
+          }else{
+            rc2 = booleanValue(azArg[2]);
+            isOk = 3;
+          }
+          sqlite3_test_control(testctrl, &rc2);
+          break;
       }
     }
     if( isOk==0 && iCtrl>=0 ){
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index ce32b85b18..1f53438142 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -8300,6 +8300,7 @@ int sqlite3_test_control(int op, ...);
 #define SQLITE_TESTCTRL_ASSERT                  12
 #define SQLITE_TESTCTRL_ALWAYS                  13
 #define SQLITE_TESTCTRL_RESERVE                 14  /* NOT USED */
+#define SQLITE_TESTCTRL_JSON_SELFCHECK          14
 #define SQLITE_TESTCTRL_OPTIMIZATIONS           15
 #define SQLITE_TESTCTRL_ISKEYWORD               16  /* NOT USED */
 #define SQLITE_TESTCTRL_SCRATCHMALLOC           17  /* NOT USED */
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index a0d5962005..83226b5750 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -4177,6 +4177,9 @@ struct Sqlite3Config {
   u8 bSmallMalloc;                  /* Avoid large memory allocations if true */
   u8 bExtraSchemaChecks;            /* Verify type,name,tbl_name in schema */
   u8 bUseLongDouble;                /* Make use of long double */
+#ifdef SQLITE_DEBUG
+  u8 bJsonSelfcheck;                /* Double-check JSON parsing */
+#endif
   int mxStrlen;                     /* Maximum string length */
   int neverCorrupt;                 /* Database is always well-formed */
   int szLookaside;                  /* Default lookaside buffer size */
diff --git a/test/fuzzcheck.c b/test/fuzzcheck.c
index 23200a5f03..d71335510d 100644
--- a/test/fuzzcheck.c
+++ b/test/fuzzcheck.c
@@ -1267,6 +1267,8 @@ int runCombinedDbSqlInput(
   }
   sqlite3_limit(cx.db, SQLITE_LIMIT_LIKE_PATTERN_LENGTH, 100);
   sqlite3_hard_heap_limit64(heapLimit);
+  rc = 1;
+  sqlite3_test_control(SQLITE_TESTCTRL_JSON_SELFCHECK, &rc);
 
   if( nDb>=20 && aDb[18]==2 && aDb[19]==2 ){
     aDb[18] = aDb[19] = 1;