diff --git a/src/hflow/transform.py b/src/hflow/transform.py
index aa1791cb..61e9d568 100644
--- a/src/hflow/transform.py
+++ b/src/hflow/transform.py
@@ -56,7 +56,6 @@
 import hashlib
 import json
 import logging
-import math
 from collections.abc import Callable, Mapping, Sequence
 from copy import copy
 from dataclasses import dataclass, field
@@ -64,6 +63,11 @@
 from typing import Any, Literal
 
 from hflow import video as video_module
+from hflow._field_guards import (
+    require_int_in_range,
+    require_positive_float,
+    require_positive_int,
+)
 from hflow._grouped_mcap_writer import (
     NO_SCHEMA_ID,
     ChannelId,
@@ -156,28 +160,11 @@ class TransformConfig:
 
     def __post_init__(self) -> None:
         """Reject invalid settings before they become a pipeline identity."""
-        if isinstance(self.crf, bool) or not isinstance(self.crf, int):
-            raise ValueError(f"crf must be an int, got {type(self.crf).__name__}")
-        if not 0 <= self.crf <= 51:
-            raise ValueError(f"crf must be between 0 and 51, got {self.crf}")
-
+        require_int_in_range(self.crf, "crf", minimum=0, maximum=51)
         if self.gop_seconds is not None:
-            if isinstance(self.gop_seconds, bool) or not isinstance(self.gop_seconds, int | float):
-                raise ValueError(
-                    f"gop_seconds must be an int or float, got {type(self.gop_seconds).__name__}"
-                )
-            if not math.isfinite(self.gop_seconds) or self.gop_seconds <= 0:
-                raise ValueError(f"gop_seconds must be positive and finite, got {self.gop_seconds}")
-
+            require_positive_float(self.gop_seconds, "gop_seconds")
         if self.chunk_size_bytes is not None:
-            if isinstance(self.chunk_size_bytes, bool) or not isinstance(
-                self.chunk_size_bytes, int
-            ):
-                raise ValueError(
-                    f"chunk_size_bytes must be an int, got {type(self.chunk_size_bytes).__name__}"
-                )
-            if self.chunk_size_bytes <= 0:
-                raise ValueError(f"chunk_size_bytes must be positive, got {self.chunk_size_bytes}")
+            require_positive_int(self.chunk_size_bytes, "chunk_size_bytes")
 
 
 @dataclass(frozen=True)
diff --git a/tests/test_transform.py b/tests/test_transform.py
index edd5dd00..dcbc662c 100644
--- a/tests/test_transform.py
+++ b/tests/test_transform.py
@@ -49,24 +49,27 @@ def test_pipeline_version_is_a_content_hash() -> None:
 
 
 @pytest.mark.parametrize(
-    ("construct", "field"),
+    ("construct", "message"),
     [
-        (lambda: TransformConfig(crf=True), "crf"),
-        (lambda: TransformConfig(crf=-1), "crf"),
-        (lambda: TransformConfig(crf=52), "crf"),
-        (lambda: TransformConfig(gop_seconds=True), "gop_seconds"),
-        (lambda: TransformConfig(gop_seconds=0), "gop_seconds"),
-        (lambda: TransformConfig(gop_seconds=float("nan")), "gop_seconds"),
-        (lambda: TransformConfig(gop_seconds=float("inf")), "gop_seconds"),
-        (lambda: TransformConfig(chunk_size_bytes=True), "chunk_size_bytes"),
-        (lambda: TransformConfig(chunk_size_bytes=0), "chunk_size_bytes"),
-        (lambda: TransformConfig(chunk_size_bytes=-1), "chunk_size_bytes"),
+        (lambda: TransformConfig(crf=True), "crf must be an int, got bool"),
+        (lambda: TransformConfig(crf=-1), "crf must be in [0, 51], got -1"),
+        (lambda: TransformConfig(crf=52), "crf must be in [0, 51], got 52"),
+        (lambda: TransformConfig(gop_seconds=True), "gop_seconds must be an int or float, got bool"),
+        (lambda: TransformConfig(gop_seconds=0), "gop_seconds must be > 0, got 0"),
+        (lambda: TransformConfig(gop_seconds=float("nan")), "gop_seconds must be finite, got nan"),
+        (lambda: TransformConfig(gop_seconds=float("inf")), "gop_seconds must be finite, got inf"),
+        (
+            lambda: TransformConfig(chunk_size_bytes=True),
+            "chunk_size_bytes must be an int, got bool",
+        ),
+        (lambda: TransformConfig(chunk_size_bytes=0), "chunk_size_bytes must be > 0, got 0"),
+        (lambda: TransformConfig(chunk_size_bytes=-1), "chunk_size_bytes must be > 0, got -1"),
     ],
 )
 def test_transform_config_rejects_invalid_numeric_settings(
-    construct: Callable[[], TransformConfig], field: str
+    construct: Callable[[], TransformConfig], message: str
 ) -> None:
-    with pytest.raises(ValueError, match=field):
+    with pytest.raises(ValueError, match=f"^{message}$"):
         construct()