diff --git a/test/ossfuzz/json_load_dump_fuzzer.cc b/test/ossfuzz/json_load_dump_fuzzer.cc
index 09f52d2..29f92f6 100644
--- a/test/ossfuzz/json_load_dump_fuzzer.cc
+++ b/test/ossfuzz/json_load_dump_fuzzer.cc
@@ -1,12 +1,37 @@
 #include <stdint.h>
+#include <stdlib.h>
 #include <sys/types.h>
+#include <inttypes.h>
 
 #include "jansson.h"
 
+static int enable_diags;
+
+#define FUZZ_DEBUG(FMT, ...)                                                  \
+        if (enable_diags)                                                     \
+        {                                                                     \
+          fprintf(stderr, FMT, ##__VA_ARGS__);                                \
+          fprintf(stderr, "\n");                                              \
+        }
+
+
+static int json_dump_counter(const char *buffer, size_t size, void *data)
+{
+  uint64_t *counter = reinterpret_cast<uint64_t *>(data);
+  *counter += size;
+  return 0;
+}
+
+
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
 {
   json_error_t error;
 
+  // Enable or disable diagnostics based on the FUZZ_VERBOSE environment flag.
+  enable_diags = (getenv("FUZZ_VERBOSE") != NULL);
+
+  FUZZ_DEBUG("Input data length: %zd", size);
+
   if (size < sizeof(size_t) + sizeof(size_t))
   {
     return 0;
@@ -17,11 +42,45 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
   data += sizeof(size_t);
   size -= sizeof(size_t);
 
+  FUZZ_DEBUG("load_flags: 0x%zx\n"
+             "& JSON_REJECT_DUPLICATES =  0x%zx\n"
+             "& JSON_DECODE_ANY =         0x%zx\n"
+             "& JSON_DISABLE_EOF_CHECK =  0x%zx\n"
+             "& JSON_DECODE_INT_AS_REAL = 0x%zx\n"
+             "& JSON_ALLOW_NUL =          0x%zx\n",
+             load_flags,
+             load_flags & JSON_REJECT_DUPLICATES,
+             load_flags & JSON_DECODE_ANY,
+             load_flags & JSON_DISABLE_EOF_CHECK,
+             load_flags & JSON_DECODE_INT_AS_REAL,
+             load_flags & JSON_ALLOW_NUL);
+
   // Use the next sizeof(size_t) bytes as dump flags.
   size_t dump_flags = *(const size_t*)data;
   data += sizeof(size_t);
   size -= sizeof(size_t);
 
+  FUZZ_DEBUG("dump_flags: 0x%zx\n"
+             "& JSON_MAX_INDENT =     0x%zx\n"
+             "& JSON_COMPACT =        0x%zx\n"
+             "& JSON_ENSURE_ASCII =   0x%zx\n"
+             "& JSON_SORT_KEYS =      0x%zx\n"
+             "& JSON_PRESERVE_ORDER = 0x%zx\n"
+             "& JSON_ENCODE_ANY =     0x%zx\n"
+             "& JSON_ESCAPE_SLASH =   0x%zx\n"
+             "& JSON_REAL_PRECISION = 0x%zx\n"
+             "& JSON_EMBED =          0x%zx\n",
+             dump_flags,
+             dump_flags & JSON_MAX_INDENT,
+             dump_flags & JSON_COMPACT,
+             dump_flags & JSON_ENSURE_ASCII,
+             dump_flags & JSON_SORT_KEYS,
+             dump_flags & JSON_PRESERVE_ORDER,
+             dump_flags & JSON_ENCODE_ANY,
+             dump_flags & JSON_ESCAPE_SLASH,
+             ((dump_flags >> 11) & 0x1F) << 11,
+             dump_flags & JSON_EMBED);
+
   // Attempt to load the remainder of the data with the given load flags.
   const char* text = reinterpret_cast<const char *>(data);
   json_t* jobj = json_loadb(text, size, load_flags, &error);
@@ -32,11 +91,10 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
   }
 
   // Attempt to dump the loaded json object with the given dump flags.
-  char* out = json_dumps(jobj, dump_flags);
-  if (out)
-  {
-    free(out);
-  }
+  uint64_t counter = 0;
+
+  json_dump_callback(jobj, json_dump_counter, &counter, dump_flags);
+  FUZZ_DEBUG("Counter function counted %" PRIu64 " bytes.", counter);
 
   if (jobj)
   {
@@ -44,4 +102,4 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
   }
 
   return 0;
-}
\ No newline at end of file
+}