diff --git a/devtools/etdump/serialize.py b/devtools/etdump/serialize.py
index 00fd1e70689..fc656057e28 100644
--- a/devtools/etdump/serialize.py
+++ b/devtools/etdump/serialize.py
@@ -10,6 +10,7 @@
 import importlib.resources as _resources
 import json
 import os
+import re
 import tempfile
 
 import executorch.devtools.etdump as etdump_package
@@ -21,6 +22,10 @@
 ETDUMP_FLATCC_SCHEMA_NAME = "etdump_schema_flatcc"
 SCALAR_TYPE_SCHEMA_NAME = "scalar_type"
 
+# flatc writes non-finite floats as bare inf, -inf, nan and -nan, which
+# json.loads rejects. String literals are matched first so they pass through.
+_FLATC_NON_FINITE_RE = re.compile(rb'("(?:[^"\\]|\\.)*")|-?\bnan\b|\binf\b')
+
 
 def _write_schema(d: str, schema_name: str) -> None:
     schema_path = os.path.join(d, "{}.fbs".format(schema_name))
@@ -39,7 +44,12 @@ def _serialize_from_etdump_to_json(etdump: ETDumpFlatCC) -> str:
 
 # from json to etdump
 def _deserialize_from_json_to_etdump_flatcc(etdump_json: bytes) -> ETDumpFlatCC:
-    etdump_json = json.loads(etdump_json)
+    etdump_json = json.loads(
+        _FLATC_NON_FINITE_RE.sub(
+            lambda m: m.group(1) or (b"Infinity" if m.group(0) == b"inf" else b"NaN"),
+            etdump_json,
+        )
+    )
     return _json_to_dataclass(etdump_json, ETDumpFlatCC)
 
 
diff --git a/devtools/etdump/tests/serialize_test.py b/devtools/etdump/tests/serialize_test.py
index 5cab3e5b2ba..a2b3dcdaf33 100644
--- a/devtools/etdump/tests/serialize_test.py
+++ b/devtools/etdump/tests/serialize_test.py
@@ -8,6 +8,7 @@
 
 import difflib
 import json
+import math
 import unittest
 from pprint import pformat
 from typing import List
@@ -140,3 +141,23 @@ def test_serialize(self) -> None:
                 )
             ),
         )
+
+    def test_serialize_non_finite_floats(self) -> None:
+        program = get_sample_etdump_flatcc()
+        debug_entry = program.run_data[0].events[3].debug_event.debug_entry
+        debug_entry.float_value = flatcc.Float(float("inf"))
+        debug_entry.double_value = flatcc.Double(float("-inf"))
+
+        deserialized_obj = deserialize_from_etdump_flatcc(
+            serialize_to_etdump_flatcc(program), size_prefixed=False
+        )
+        self.assertEqual(program, deserialized_obj)
+
+        debug_entry.double_value = flatcc.Double(float("nan"))
+        deserialized_obj = deserialize_from_etdump_flatcc(
+            serialize_to_etdump_flatcc(program), size_prefixed=False
+        )
+        deserialized_entry = deserialized_obj.run_data[0].events[3].debug_event
+        self.assertTrue(
+            math.isnan(deserialized_entry.debug_entry.double_value.double_val)
+        )