diff --git a/sphinx/addnodes.py b/sphinx/addnodes.py
index 2ebc1432ab6..788f9bfa25a 100644
--- a/sphinx/addnodes.py
+++ b/sphinx/addnodes.py
@@ -119,6 +119,19 @@ def extract_original_messages(self) -> List[str]:
 # Domain-specific object descriptions (class, function etc.)
 #############################################################
 
+class _desc_classes_injector:
+    """Helper base class for injecting a fixes list of classes.
+
+    Use as the first base class.
+    """
+
+    classes = []  # type: List[str]
+
+    def __init__(self, *args, **kwargs) -> None:
+        super().__init__(*args, **kwargs)
+        self['classes'].extend(self.classes)
+
+
 # Top-level nodes
 #################
 
@@ -175,20 +188,26 @@ class desc_content(nodes.General, nodes.Element):
 
 # nodes to use within a desc_signature or desc_signature_line
 
-class desc_name(nodes.Part, nodes.Inline, nodes.FixedTextElement):
+class desc_name(_desc_classes_injector, nodes.Part, nodes.Inline, nodes.FixedTextElement):
     """Node for the main object name.
 
     For example, in the declaration of a Python class ``MyModule.MyClass``,
     the main name is ``MyClass``.
+
+    This node always has the class ``sig-name``.
     """
+    classes = ['sig-name', 'descname']  # 'descname' is for backwards compatibility
 
 
-class desc_addname(nodes.Part, nodes.Inline, nodes.FixedTextElement):
+class desc_addname(_desc_classes_injector, nodes.Part, nodes.Inline, nodes.FixedTextElement):
     """Node for additional name parts for an object.
 
     For example, in the declaration of a Python class ``MyModule.MyClass``,
     the additional name part is ``MyModule.``.
+
+    This node always has the class ``sig-prename``.
     """
+    classes = ['sig-prename', 'descclassname']  # 'descclassname' is for backwards compatibility
 
 
 # compatibility alias
@@ -237,7 +256,7 @@ class desc_annotation(nodes.Part, nodes.Inline, nodes.FixedTextElement):
 # in SigElementFallbackTransform.
 # When adding a new one, add it to SIG_ELEMENTS.
 
-class desc_sig_element(nodes.inline):
+class desc_sig_element(nodes.inline, _desc_classes_injector):
     """Common parent class of nodes for inline text of a signature."""
     classes = []  # type: List[str]
 
diff --git a/sphinx/writers/html.py b/sphinx/writers/html.py
index 52ab359a7f6..1823ed45cc7 100644
--- a/sphinx/writers/html.py
+++ b/sphinx/writers/html.py
@@ -149,8 +149,14 @@ def depart_desc_content(self, node: Element) -> None:
     # Nodes for high-level structure in signatures
     ##############################################
 
+    def visit_desc_name(self, node: Element) -> None:
+        self.body.append(self.starttag(node, 'code', ''))
+
+    def depart_desc_name(self, node: Element) -> None:
+        self.body.append('</code>')
+
     def visit_desc_addname(self, node: Element) -> None:
-        self.body.append(self.starttag(node, 'code', '', CLASS='descclassname'))
+        self.body.append(self.starttag(node, 'code', ''))
 
     def depart_desc_addname(self, node: Element) -> None:
         self.body.append('</code>')
@@ -167,12 +173,6 @@ def visit_desc_returns(self, node: Element) -> None:
     def depart_desc_returns(self, node: Element) -> None:
         pass
 
-    def visit_desc_name(self, node: Element) -> None:
-        self.body.append(self.starttag(node, 'code', '', CLASS='descname'))
-
-    def depart_desc_name(self, node: Element) -> None:
-        self.body.append('</code>')
-
     def visit_desc_parameterlist(self, node: Element) -> None:
         self.body.append('<span class="sig-paren">(</span>')
         self.first_param = 1
diff --git a/sphinx/writers/html5.py b/sphinx/writers/html5.py
index 9835a9ee84e..3b2523fddb8 100644
--- a/sphinx/writers/html5.py
+++ b/sphinx/writers/html5.py
@@ -121,13 +121,13 @@ def depart_desc_content(self, node: Element) -> None:
     ##############################################
 
     def visit_desc_name(self, node: Element) -> None:
-        self.body.append(self.starttag(node, 'code', '', CLASS='sig-name descname'))
+        self.body.append(self.starttag(node, 'code', ''))
 
     def depart_desc_name(self, node: Element) -> None:
         self.body.append('</code>')
 
     def visit_desc_addname(self, node: Element) -> None:
-        self.body.append(self.starttag(node, 'code', '', CLASS='sig-prename descclassname'))
+        self.body.append(self.starttag(node, 'code', ''))
 
     def depart_desc_addname(self, node: Element) -> None:
         self.body.append('</code>')