diff --git a/HACKING.rst b/HACKING.rst
index e3d49e77..64a6ddcc 100644
--- a/HACKING.rst
+++ b/HACKING.rst
@@ -152,6 +152,8 @@ Example::
       },
   }
 
+Do not use ``locals()`` for formatting strings, it is not clear as using
+explicit dictionaries and can hide errors during refactoring.
 
 Calling Methods
 ---------------
diff --git a/hacking/core.py b/hacking/core.py
index d1cd1dfd..ff757327 100755
--- a/hacking/core.py
+++ b/hacking/core.py
@@ -586,6 +586,28 @@ def hacking_docstring_multiline_start(physical_line, previous_logical, tokens):
                         "should start with a summary")
 
 
+@flake8ext
+def hacking_no_locals(logical_line, physical_line, tokens):
+    """Do not use locals() for string formatting.
+
+    Okay: 'locals()'
+    Okay: 'locals'
+    Okay: locals()
+    Okay: print(locals())
+    H501: print("%(something)" % locals())
+    Okay: print("%(something)" % locals())  # noqa
+    """
+    if pep8.noqa(physical_line):
+        return
+    for_formatting = False
+    for token_type, text, start, _, _ in tokens:
+        if text == "%" and token_type == tokenize.OP:
+            for_formatting = True
+        if (for_formatting and token_type == tokenize.NAME and text ==
+                "locals" and "locals()" in logical_line):
+            yield (start[1], "H501: Do not use locals() for string formatting")
+
+
 @flake8ext
 def hacking_no_cr(physical_line):
     r"""Check that we only use newlines not carriage returns.
diff --git a/setup.cfg b/setup.cfg
index ac41d068..ce4e4abe 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -41,6 +41,7 @@ flake8.extension =
     H402 = hacking.core:hacking_docstring_one_line
     H403 = hacking.core:hacking_docstring_multiline_end
     H404 = hacking.core:hacking_docstring_multiline_start
+    H501 = hacking.core:hacking_no_locals
     H601 = hacking.core:hacking_no_cr
     H700 = hacking.core:hacking_localization_strings
     H801 = hacking.core:OnceGitCheckCommitTitleBug