diff --git a/CHANGES b/CHANGES
index 4cd8ac3d335..2291738cdff 100644
--- a/CHANGES
+++ b/CHANGES
@@ -11,6 +11,9 @@ Bugs fixed
 
 * Fix regression in ``autodoc.Documenter.parse_name()``.
 * Fix regression in JSON serialisation.
+* #11634: Fixed two more bugs in inheritance diagrams that resulted in
+  broken links.
+  Patch by Albert Shih.
 
 Release 7.2.2 (released Aug 17, 2023)
 =====================================
diff --git a/sphinx/ext/graphviz.py b/sphinx/ext/graphviz.py
index 00c9e0b4164..cfab47efead 100644
--- a/sphinx/ext/graphviz.py
+++ b/sphinx/ext/graphviz.py
@@ -235,10 +235,11 @@ def fix_svg_relative_paths(self: SphinxTranslator, filepath: str) -> None:
             # not a relative link
             continue
 
-        old_path = path.join(self.builder.outdir, url)
+        docdir = path.dirname(path.join(self.builder.outdir, self.builder.current_docname))
+        old_path = path.join(docdir, url)
         new_path = path.relpath(
             old_path,
-            start=path.join(self.builder.outdir, self.builder.imgpath),
+            start=path.join(docdir, self.builder.imgpath),
         )
         modified_url = urlunsplit((scheme, hostname, new_path, query, fragment))
 
diff --git a/sphinx/ext/inheritance_diagram.py b/sphinx/ext/inheritance_diagram.py
index 838fe40bc74..24d147b50b0 100644
--- a/sphinx/ext/inheritance_diagram.py
+++ b/sphinx/ext/inheritance_diagram.py
@@ -34,6 +34,7 @@ class E(B): pass
 import hashlib
 import inspect
 import re
+from os import path
 from collections.abc import Iterable, Sequence
 from importlib import import_module
 from typing import TYPE_CHECKING, Any, cast
@@ -417,7 +418,7 @@ def html_visit_inheritance_diagram(self: HTML5Translator, node: inheritance_diag
 
     # Create a mapping from fully-qualified class names to URLs.
     graphviz_output_format = self.builder.env.config.graphviz_output_format.upper()
-    current_filename = self.builder.current_docname + self.builder.out_suffix
+    current_filename = path.basename(self.builder.current_docname + self.builder.out_suffix)
     urls = {}
     pending_xrefs = cast(Iterable[addnodes.pending_xref], node)
     for child in pending_xrefs:
diff --git a/tests/roots/test-ext-inheritance_diagram/subdir/index.rst b/tests/roots/test-ext-inheritance_diagram/subdir/index.rst
index bfd4aa88a2d..a3b79730eb7 100644
--- a/tests/roots/test-ext-inheritance_diagram/subdir/index.rst
+++ b/tests/roots/test-ext-inheritance_diagram/subdir/index.rst
@@ -4,4 +4,6 @@ test-ext-inheritance_diagram subdirectory
 
 .. inheritance-diagram:: test.DocMainLevel
 
+.. inheritance-diagram:: test.DocLowerLevel
+
 .. py:class:: test.DocLowerLevel