diff --git a/novelwriter/common.py b/novelwriter/common.py
index cdb10278..b658cf6d 100644
--- a/novelwriter/common.py
+++ b/novelwriter/common.py
@@ -29,7 +29,7 @@ import logging
 import unicodedata
 import xml.etree.ElementTree as ET
 
-from typing import Any, Literal
+from typing import TYPE_CHECKING, Any, Literal
 from pathlib import Path
 from datetime import datetime
 from configparser import ConfigParser
@@ -43,6 +43,9 @@ from novelwriter.enum import nwItemClass, nwItemType, nwItemLayout
 from novelwriter.error import logException
 from novelwriter.constants import nwConst, nwUnicode
 
+if TYPE_CHECKING:  # pragma: no cover
+    from typing import TypeGuard  # Requires Python 3.10
+
 logger = logging.getLogger(__name__)
 
 
@@ -104,15 +107,6 @@ def checkBool(value: Any, default: bool) -> bool:
     return default
 
 
-def checkHandle(value, default, allowNone=False):
-    """Check if a value is a handle."""
-    if allowNone and (value is None or value == "None"):
-        return None
-    if isHandle(value):
-        return str(value)
-    return default
-
-
 def checkUuid(value: Any, default: str) -> str:
     """Try to process a value as an UUID, or return a default."""
     try:
@@ -135,7 +129,7 @@ def checkPath(value: Any, default: Path) -> Path:
 #  Validator Functions
 ##
 
-def isHandle(value: Any) -> bool:
+def isHandle(value: Any) -> TypeGuard[str]:
     """Check if a string is a valid novelWriter handle.
     Note: This is case sensitive. Must be lower case!
     """
@@ -149,7 +143,7 @@ def isHandle(value: Any) -> bool:
     return True
 
 
-def isTitleTag(value: Any) -> bool:
+def isTitleTag(value: Any) -> TypeGuard[str]:
     """Check if a string is a valid title tag string."""
     if not isinstance(value, str):
         return False
@@ -163,19 +157,19 @@ def isTitleTag(value: Any) -> bool:
     return True
 
 
-def isItemClass(value: str) -> bool:
+def isItemClass(value: Any) -> TypeGuard[str]:
     """Check if a string is a valid nwItemClass identifier."""
-    return value in nwItemClass.__members__
+    return isinstance(value, str) and value in nwItemClass.__members__
 
 
-def isItemType(value: str) -> bool:
+def isItemType(value: Any) -> TypeGuard[str]:
     """Check if a string is a valid nwItemType identifier."""
-    return value in nwItemType.__members__
+    return isinstance(value, str) and value in nwItemType.__members__
 
 
-def isItemLayout(value: str) -> bool:
+def isItemLayout(value: Any) -> TypeGuard[str]:
     """Check if a string is a valid nwItemLayout identifier."""
-    return value in nwItemLayout.__members__
+    return isinstance(value, str) and value in nwItemLayout.__members__
 
 
 def hexToInt(value: Any, default: int = 0) -> int:
@@ -189,8 +183,7 @@ def hexToInt(value: Any, default: int = 0) -> int:
 
 
 def minmax(value: int, minVal: int, maxVal: int) -> int:
-    """Make sure an integer is between min and max value (inclusive).
-    """
+    """Check that an value is between min and max value (inclusive)."""
     return min(maxVal, max(minVal, value))
 
 
diff --git a/tests/test_base/test_base_common.py b/tests/test_base/test_base_common.py
index a45571cf..f074be0f 100644
--- a/tests/test_base/test_base_common.py
+++ b/tests/test_base/test_base_common.py
@@ -33,9 +33,9 @@ from PyQt5.QtGui import QDesktopServices
 from PyQt5.QtCore import QUrl
 
 from novelwriter.common import (
-    checkBool, checkFloat, checkHandle, checkInt, checkIntTuple, checkPath,
-    checkString, checkStringNone, checkUuid, formatInt, formatTime,
-    formatTimeStamp, formatVersion, fuzzyTime, getFileSize, hexToInt, isHandle, isItemClass,
+    checkBool, checkFloat, checkInt, checkIntTuple, checkPath, checkString,
+    checkStringNone, checkUuid, formatInt, formatTime, formatTimeStamp,
+    formatVersion, fuzzyTime, getFileSize, hexToInt, isHandle, isItemClass,
     isItemLayout, isItemType, isTitleTag, jsonEncode, makeFileNameSafe, minmax,
     numberToRoman, NWConfigParser, openExternalPath, readTextFile, simplified,
     transferCase, xmlIndent, yesNo
@@ -151,19 +151,6 @@ def testBaseCommon_checkBool():
 # END Test testBaseCommon_checkBool
 
 
-@pytest.mark.base
-def testBaseCommon_checkHandle():
-    """Test the checkHandle function."""
-    assert checkHandle("None", 1, True) is None
-    assert checkHandle("None", 1, False) == 1
-    assert checkHandle(None, 1, True) is None
-    assert checkHandle(None, 1, False) == 1
-    assert checkHandle("47666c91c7ccf", None, False) == "47666c91c7ccf"
-    assert checkHandle("h7666c91c7ccf", None, False) is None
-
-# END Test testBaseCommon_checkHandle
-
-
 @pytest.mark.base
 def testBaseCommon_checkUuid():
     """Test the checkUuid function."""
@@ -236,7 +223,7 @@ def testBaseCommon_isItemClass():
 
     # Invalid
     assert isItemClass("None") is False
-    assert isItemClass(None) is False  # type: ignore
+    assert isItemClass(None) is False
     assert isItemClass("STUFF") is False
 
 # END Test testBaseCommon_isItemClass