diff --git a/mps/.readthedocs.yaml b/mps/.readthedocs.yaml
index 0a269c4fb07..8ae20323cd0 100644
--- a/mps/.readthedocs.yaml
+++ b/mps/.readthedocs.yaml
@@ -26,6 +26,7 @@ python:
 
 sphinx:
   configuration: manual/source/conf.py
+  fail_on_warning: true
 
 # A. REFERENCES
 #
diff --git a/mps/design/object-debug.txt b/mps/design/object-debug.txt
index 3ecea76544e..66f1ba958f3 100644
--- a/mps/design/object-debug.txt
+++ b/mps/design/object-debug.txt
@@ -347,10 +347,6 @@ _`.interface.tags.alloc`: Two functions to extend the existing
 _`.interface.tags.walker.type`: Type of walker function for
 ``mps_pool_walk()`` and ``mps_arena_walk()``.
 
-``void mps_pool_walk(mps_arena_t arena, mps_pool_t pool, mps_objects_step_t step, void *p)``
-
-``void mps_arena_walk(mps_arena_t arena, mps_objects_step_t step, void *p)``
-
 _`.interface.tags.walker`: Functions to walk all the allocated
 objects in an arena (only client pools in this case),
 ``format`` and ``tag_data`` can be ``NULL`` (``tag_data`` really wants
diff --git a/mps/manual/Makefile b/mps/manual/Makefile
index 8ad7787c3dc..25615b85712 100644
--- a/mps/manual/Makefile
+++ b/mps/manual/Makefile
@@ -6,7 +6,7 @@
 
 # You can set these variables from the command line.
 PYTHON        = python3
-SPHINXOPTS    =
+SPHINXOPTS    = -T -W --keep-going
 SPHINXBUILD   = tool/bin/sphinx-build
 PAPER         =
 BUILDDIR      = .
diff --git a/mps/manual/source/extensions/mps/__init__.py b/mps/manual/source/extensions/mps/__init__.py
index 9fa0c43f04c..6c4900b86d6 100644
--- a/mps/manual/source/extensions/mps/__init__.py
+++ b/mps/manual/source/extensions/mps/__init__.py
@@ -56,12 +56,13 @@ class MpsDirective(Directive):
         else:
             return
         if hasattr(cls, 'node_class') and hasattr(cls, 'visit'):
-            app.add_node(cls.node_class, html=cls.visit, latex=cls.visit,
+            app.add_node(cls.node_class, override=True,
+                         html=cls.visit, latex=cls.visit,
                          text=cls.visit, man=cls.visit)
         if hasattr(cls, 'domain'):
-            app.add_directive_to_domain(cls.domain, name, cls)
+            app.add_directive_to_domain(cls.domain, name, cls, override=True)
         else:
-            app.add_directive(name, cls)
+            app.add_directive(name, cls, override=True)
 
 class MpsPrefixDirective(MpsDirective):
     domain = 'mps'
diff --git a/mps/manual/source/topic/scanning.rst b/mps/manual/source/topic/scanning.rst
index dd481947c41..b8809941850 100644
--- a/mps/manual/source/topic/scanning.rst
+++ b/mps/manual/source/topic/scanning.rst
@@ -557,7 +557,7 @@ the scanners, found in ``scan.c`` in the MPS source code.
     .. note::
 
         The reason that :c:data:`base` and :c:data:`limit` have type
-        :c:type:`void *` and not :c:type:`mps_addr_t` is that the
+        ``void *`` and not :c:type:`mps_addr_t` is that the
         latter is used only for :term:`addresses` managed by the MPS,
         but :c:type:`mps_area_scan_t` may also be used to scan
         :term:`roots` that are not managed by the MPS.