diff --git a/CHANGES b/CHANGES
index 1d1fa0075ec..50962197c99 100644
--- a/CHANGES
+++ b/CHANGES
@@ -84,6 +84,8 @@ Bugs fixed
 * #11473: Type annotations containing :py:data:`~typing.Literal` enumeration
   values now render correctly.
   Patch by Bénédikt Tran.
+* #11591: Fix support for C coverage in ``sphinx.ext.coverage`` extension.
+  Patch by Stephen Finucane.
 
 Testing
 -------
diff --git a/sphinx/domains/c.py b/sphinx/domains/c.py
index ea5a1a5db2f..f02c72944f2 100644
--- a/sphinx/domains/c.py
+++ b/sphinx/domains/c.py
@@ -77,7 +77,7 @@
     'thread_local',
 ]
 
-# these are ordered by preceedence
+# these are ordered by precedence
 _expression_bin_ops = [
     ['||', 'or'],
     ['&&', 'and'],
diff --git a/sphinx/ext/coverage.py b/sphinx/ext/coverage.py
index 030bf84b397..e3d9745e397 100644
--- a/sphinx/ext/coverage.py
+++ b/sphinx/ext/coverage.py
@@ -114,8 +114,9 @@ def write(self, *ignored: Any) -> None:
         self.write_c_coverage()
 
     def build_c_coverage(self) -> None:
-        # Fetch all the info from the header files
-        c_objects = self.env.domaindata['c']['objects']
+        c_objects = {}
+        for obj in self.env.domains['c'].get_objects():
+            c_objects[obj[2]] = obj[1]
         for filename in self.c_sourcefiles:
             undoc: set[tuple[str, str]] = set()
             with open(filename, encoding="utf-8") as f:
@@ -124,7 +125,11 @@ def build_c_coverage(self) -> None:
                         match = regex.match(line)
                         if match:
                             name = match.groups()[0]
-                            if name not in c_objects:
+                            if key not in c_objects:
+                                undoc.add((key, name))
+                                continue
+
+                            if name not in c_objects[key]:
                                 for exp in self.c_ignorexps.get(key, []):
                                     if exp.match(name):
                                         break
diff --git a/tests/roots/test-root/objects.txt b/tests/roots/test-root/objects.txt
index 1a1392b9e66..ed5f2c25b48 100644
--- a/tests/roots/test-root/objects.txt
+++ b/tests/roots/test-root/objects.txt
@@ -133,6 +133,8 @@ C items
 
 .. c:var:: int sphinx_global
 
+.. c:function:: PyObject* Py_SphinxFoo(void)
+
 
 Javascript items
 ================
diff --git a/tests/roots/test-root/special/api.h b/tests/roots/test-root/special/api.h
index 7c137e03951..2bf23826b99 100644
--- a/tests/roots/test-root/special/api.h
+++ b/tests/roots/test-root/special/api.h
@@ -1 +1,2 @@
-PyAPI_FUNC(PyObject *) Py_SphinxTest();
+PyAPI_FUNC(PyObject *) Py_SphinxTest(void);
+PyAPI_FUNC(PyObject *) Py_SphinxFoo(void);