diff --git a/raillabel_providerkit/validation/issue.py b/raillabel_providerkit/validation/issue.py
index 5c490fd..c654ee6 100644
--- a/raillabel_providerkit/validation/issue.py
+++ b/raillabel_providerkit/validation/issue.py
@@ -3,6 +3,7 @@
 
 from dataclasses import dataclass
 from enum import Enum
+from uuid import UUID
 
 
 class IssueType(Enum):
@@ -17,9 +18,9 @@ class IssueType(Enum):
 class IssueIdentifiers:
     """Information for locating an issue."""
 
-    annotation: str | None = None
-    frame: str | None = None
-    object: str | None = None
+    annotation: UUID | None = None
+    frame: int | None = None
+    object: UUID | None = None
     sensor: str | None = None
 
 
diff --git a/raillabel_providerkit/validation/validate_empty_frames/validate_empty_frames.py b/raillabel_providerkit/validation/validate_empty_frames/validate_empty_frames.py
index c7b70bf..2ba798e 100644
--- a/raillabel_providerkit/validation/validate_empty_frames/validate_empty_frames.py
+++ b/raillabel_providerkit/validation/validate_empty_frames/validate_empty_frames.py
@@ -5,27 +5,25 @@
 
 import raillabel
 
+from raillabel_providerkit.validation import Issue, IssueIdentifiers, IssueType
 
-def validate_empty_frames(scene: raillabel.Scene) -> list[str]:
-    """Validate whether all frames of a scene have at least one annotation.
-
-    Parameters
-    ----------
-    scene : raillabel.Scene
-        Scene, that should be validated.
 
-    Returns
-    -------
-    list[str]
-        list of all empty frame errors in the scene. If an empty list is returned, then there are no
-        errors present.
+def validate_empty_frames(scene: raillabel.Scene) -> list[Issue]:
+    """Validate whether all frames of a scene have at least one annotation.
 
+    If an empty list is returned, then there are no errors present.
     """
-    errors: list[str] = []
+    errors = []
 
     for frame_uid, frame in scene.frames.items():
         if _is_frame_empty(frame):
-            errors.append("Frame " + str(frame_uid) + " has no annotations!")
+            errors.append(
+                Issue(
+                    type=IssueType.EMPTY_FRAMES,
+                    reason="This frame has no annotations.",
+                    identifiers=IssueIdentifiers(frame=frame_uid),
+                )
+            )
 
     return errors
 
diff --git a/tests/test_raillabel_providerkit/validation/validate_empty_frame/test_validate_empty_frames.py b/tests/test_raillabel_providerkit/validation/validate_empty_frame/test_validate_empty_frames.py
index 7f1eea1..d4c5763 100644
--- a/tests/test_raillabel_providerkit/validation/validate_empty_frame/test_validate_empty_frames.py
+++ b/tests/test_raillabel_providerkit/validation/validate_empty_frame/test_validate_empty_frames.py
@@ -7,6 +7,7 @@
     _is_frame_empty,
     validate_empty_frames,
 )
+from raillabel_providerkit.validation import Issue, IssueIdentifiers, IssueType
 
 
 def test_is_frame_empty__true(empty_frame):
@@ -59,10 +60,12 @@ def test_validate_empty_frames__error_message_contains_indentifying_info(empty_f
         0: empty_frame,
     }
 
-    error_message = validate_empty_frames(scene)[0].lower()
-    assert "frame" in error_message
-    assert "0" in error_message
-    assert "empty" in error_message or "no annotations" in error_message
+    actual = validate_empty_frames(scene)[0]
+    assert actual == Issue(
+        type=IssueType.EMPTY_FRAMES,
+        reason="This frame has no annotations.",
+        identifiers=IssueIdentifiers(frame=0),
+    )
 
 
 if __name__ == "__main__":