diff --git a/pygit2/config.py b/pygit2/config.py
index f05a8d13..5ffb6896 100644
--- a/pygit2/config.py
+++ b/pygit2/config.py
@@ -73,7 +73,7 @@ def _next_entry(self) -> 'ConfigEntry':
 
 
 class ConfigMultivarIterator(ConfigIterator):
-    def __next__(self) -> str:  # type: ignore[override]
+    def __next__(self) -> str | None:  # type: ignore[override]
         entry = self._next_entry()
         return entry.value
 
@@ -137,7 +137,7 @@ def __contains__(self, key: str | bytes) -> bool:
 
         return True
 
-    def __getitem__(self, key: str | bytes) -> str:
+    def __getitem__(self, key: str | bytes) -> str | None:
         """
         When using the mapping interface, the value is returned as a string. In
         order to apply the git-config parsing rules, you can use
@@ -365,8 +365,8 @@ def raw_name(self) -> bytes:
         return ffi.string(self._entry.name)
 
     @cached_property
-    def raw_value(self) -> bytes:
-        return ffi.string(self.c_value)
+    def raw_value(self) -> bytes | None:
+        return ffi.string(self.c_value) if self.c_value != ffi.NULL else None
 
     @cached_property
     def level(self) -> int:
@@ -379,6 +379,6 @@ def name(self) -> str:
         return self.raw_name.decode('utf-8')
 
     @property
-    def value(self) -> str:
+    def value(self) -> str | None:
         """The entry's value as a string."""
-        return self.raw_value.decode('utf-8')
+        return self.raw_value.decode('utf-8') if self.raw_value is not None else None
diff --git a/test/test_config.py b/test/test_config.py
index 247d55c5..2d1a2a11 100644
--- a/test/test_config.py
+++ b/test/test_config.py
@@ -185,6 +185,35 @@ def test_iterator(config: Config) -> None:
     assert lst['core.bare']
 
 
+def test_valueless_key_iteration() -> None:
+    # A valueless key (no `= value`) has a NULL value pointer in libgit2.
+    # Iterating over such entries must not raise a RuntimeError.
+    with open(CONFIG_FILENAME, 'w') as new_file:
+        new_file.write('[section]\n\tvaluelesskey\n\tnormalkey = somevalue\n')
+
+    config = Config()
+    config.add_file(CONFIG_FILENAME, 6)
+
+    entries = {entry.name: entry for entry in config}
+    assert 'section.valuelesskey' in entries
+    assert 'section.normalkey' in entries
+
+
+def test_valueless_key_value() -> None:
+    # A valueless key must expose value=None and raw_value=None.
+    with open(CONFIG_FILENAME, 'w') as new_file:
+        new_file.write('[section]\n\tvaluelesskey\n\tnormalkey = somevalue\n')
+
+    config = Config()
+    config.add_file(CONFIG_FILENAME, 6)
+
+    entries = {entry.name: entry for entry in config}
+    assert entries['section.valuelesskey'].raw_value is None
+    assert entries['section.valuelesskey'].value is None
+    assert entries['section.normalkey'].raw_value == b'somevalue'
+    assert entries['section.normalkey'].value == 'somevalue'
+
+
 def test_parsing() -> None:
     assert Config.parse_bool('on')
     assert Config.parse_bool('1')