diff --git a/CHANGELOG.md b/CHANGELOG.md
index 57deee3..c306f46 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,9 @@ All notable changes to SkillEvaluator are documented in this file.
 
 ### Fixed
 
+- Unpinned-dependency warnings are no longer suppressed by comparison
+  operators inside PEP 508 environment markers; requirements such as
+  `pkg; python_version < "3.13"` are now correctly reported.
 - `--llm-verify` now refuses to send file context from paths outside the
   skill root, including `..`, absolute paths, and outbound file symlinks.
 - Gitleaks path allowlist now skips test/example/fixture/mock directories
diff --git a/src/skillevaluator/validators/hygiene.py b/src/skillevaluator/validators/hygiene.py
index 76cea31..9d34e9f 100644
--- a/src/skillevaluator/validators/hygiene.py
+++ b/src/skillevaluator/validators/hygiene.py
@@ -173,10 +173,15 @@ def _check_requirements_file(self, req_file: Path) -> ValidationResult:
                 continue
 
             pkg_name = match.group(1).lower()
+            # Marker comparisons do not constrain the package version. Detect
+            # direct references before the marker so an "@" inside a marker
+            # value cannot hide an otherwise unpinned requirement.
+            requirement_part = line.partition(";")[0]
+            is_direct_reference = "@" in requirement_part
 
             if pkg_name in banned_lower:
                 result.add_error(f"{req_file.name}:{line_num} - Banned package: {pkg_name}")
-            elif not re.search(r"[=<>!]", line):
+            elif not is_direct_reference and not re.search(r"[=<>!]", requirement_part):
                 result.add_warning(f"{req_file.name}:{line_num} - Unpinned: {line}")
 
         if not result.errors and not result.warnings:
diff --git a/tests/validators/test_hygiene.py b/tests/validators/test_hygiene.py
index 72a3de1..d4e0e40 100644
--- a/tests/validators/test_hygiene.py
+++ b/tests/validators/test_hygiene.py
@@ -360,6 +360,65 @@ def test_detects_unpinned_dependencies(self, tmp_path: Path):
         all_messages = result.errors + result.warnings
         assert any("unpinned" in m.lower() for m in all_messages)
 
+    @pytest.mark.parametrize(
+        "requirement",
+        [
+            'requests; python_version < "3.13"',
+            'requests; python_version != "3.12"',
+            'requests;python_version<"3.13"',
+            'requests ; python_version < "3.13"',
+            'requests; sys_platform == "win32"',
+            'requests; implementation_name == "cpython@corp"',
+            'requests[security]; python_version >= "3.9"',
+        ],
+    )
+    def test_environment_marker_comparisons_do_not_hide_unpinned_requirements(
+        self, tmp_path: Path, requirement: str
+    ):
+        """Marker operators must not count as package version constraints."""
+        requirements = tmp_path / "requirements.txt"
+        requirements.write_text(f"{requirement}\n", encoding="utf-8")
+
+        result = HygieneValidator()._check_requirements_file(requirements)
+
+        assert result.errors == []
+        assert result.warnings == [f"requirements.txt:1 - Unpinned: {requirement}"]
+
+    @pytest.mark.parametrize(
+        "requirement",
+        [
+            'requests>=2; python_version < "3.13"',
+            "requests>=2.0,<3.0",
+            "requests==2.31.0",
+            "requests~=2.31",
+            "requests!=2.30.0",
+            "requests @ https://example.invalid/requests.whl",
+            "requests @ https://example.invalid/a;v=1/requests.whl",
+            'requests @ https://example.invalid/requests.whl ; python_version < "3.13"',
+        ],
+    )
+    def test_marker_handling_preserves_constrained_and_direct_requirements(
+        self, tmp_path: Path, requirement: str
+    ):
+        """Existing version constraints and direct-reference behavior remain accepted."""
+        requirements = tmp_path / "requirements.txt"
+        requirements.write_text(f"{requirement}\n", encoding="utf-8")
+
+        result = HygieneValidator()._check_requirements_file(requirements)
+
+        assert result.errors == []
+        assert result.warnings == []
+
+    def test_banned_requirement_with_marker_remains_an_error(self, tmp_path: Path):
+        """Banned-package errors keep precedence over marker-aware warnings."""
+        requirements = tmp_path / "requirements.txt"
+        requirements.write_text('pycrypto; python_version < "3.13"\n', encoding="utf-8")
+
+        result = HygieneValidator()._check_requirements_file(requirements)
+
+        assert result.errors == ["requirements.txt:1 - Banned package: pycrypto"]
+        assert result.warnings == []
+
     def test_detects_banned_packages(self, tmp_path: Path):
         """Test detection of banned/deprecated packages."""
         skill_dir = tmp_path / "banned-deps-skill"