diff --git a/sphinx/ext/mathbase.py b/sphinx/ext/mathbase.py
index 15218963f..513ddd62a 100644
--- a/sphinx/ext/mathbase.py
+++ b/sphinx/ext/mathbase.py
@@ -86,6 +86,7 @@ class MathDomain(Domain):
                 newnode['target'] = target
                 return newnode
             else:
+                # TODO: perhaps use rather a sphinx-core provided prefix here?
                 node_id = make_id('equation-%s' % target)
                 if env.config.math_numfig and env.config.numfig:
                     if docname in env.toc_fignumbers:
diff --git a/sphinx/writers/latex.py b/sphinx/writers/latex.py
index bdb2a92b3..1558a29d7 100644
--- a/sphinx/writers/latex.py
+++ b/sphinx/writers/latex.py
@@ -1960,6 +1960,7 @@ class LaTeXTranslator(nodes.NodeVisitor):
                 return
 
             # equations also need no extra blank line nor hypertarget
+            # TODO: fix this dependency on mathbase extension internals
             if id.startswith('equation-'):
                 return