diff --git a/docs/release_notes.rst b/docs/release_notes.rst
index cf0b6c9a..35ffd894 100644
--- a/docs/release_notes.rst
+++ b/docs/release_notes.rst
@@ -4,6 +4,12 @@ Release Notes
 **pydocstyle** version numbers follow the
 `Semantic Versioning <http://semver.org/>`_ specification.
 
+x.x.x - Current Development Version
+-----------------------------------
+
+* The error code D300 is now also being reported if a docstring has
+  uppercase literals (``R`` or ``U``) as prefix (#176).
+
 1.0.0 - January 30th, 2016
 --------------------------
 
diff --git a/src/pydocstyle.py b/src/pydocstyle.py
index 3b79af83..27e92895 100644
--- a/src/pydocstyle.py
+++ b/src/pydocstyle.py
@@ -1554,15 +1554,17 @@ def check_triple_double_quotes(self, definition, docstring):
               """ quotes in its body.
 
         '''
-        if (docstring and '"""' in ast.literal_eval(docstring) and
-                docstring.startswith(("'''", "r'''", "u'''", "ur'''"))):
-            # Allow ''' quotes if docstring contains """, because otherwise """
-            # quotes could not be expressed inside docstring.  Not in PEP 257.
-            return
-        if docstring and not docstring.startswith(
-                ('"""', 'r"""', 'u"""', 'ur"""')):
-            quotes = "'''" if "'''" in docstring[:4] else "'"
-            return D300(quotes)
+        if docstring:
+            opening = docstring[:5].lower()
+            if '"""' in ast.literal_eval(docstring) and opening.startswith(
+                    ("'''", "r'''", "u'''", "ur'''")):
+                # Allow ''' quotes if docstring contains """, because
+                # otherwise """ quotes could not be expressed inside
+                # docstring. Not in PEP 257.
+                return
+            if not opening.startswith(('"""', 'r"""', 'u"""', 'ur"""')):
+                quotes = "'''" if "'''" in opening else "'"
+                return D300(quotes)
 
     @check_for(Definition)
     def check_backslashes(self, definition, docstring):
diff --git a/src/tests/test_cases/test.py b/src/tests/test_cases/test.py
index 7d6bad06..8ee07c99 100644
--- a/src/tests/test_cases/test.py
+++ b/src/tests/test_cases/test.py
@@ -218,23 +218,44 @@ def multiline():
 
 
 @expect('D300: Use """triple double quotes""" (found \'\'\'-quotes)')
-def lsfklkjllkjl():
+def triple_single_quotes_raw():
     r'''Summary.'''
 
 
+@expect('D300: Use """triple double quotes""" (found \'\'\'-quotes)')
+def triple_single_quotes_raw_uppercase():
+    R'''Summary.'''
+
+
 @expect('D300: Use """triple double quotes""" (found \'-quotes)')
-def lalskklkjllkjl():
+def single_quotes_raw():
     r'Summary.'
 
 
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
+def single_quotes_raw_uppercase():
+    R'Summary.'
+
+
+@expect('D300: Use """triple double quotes""" (found \'-quotes)')
 @expect('D301: Use r""" if any backslashes in a docstring')
-def lalsksdewnlkjl():
+def single_quotes_raw_uppercase_backslash():
+    R'Sum\mary.'
+
+
+@expect('D301: Use r""" if any backslashes in a docstring')
+def double_quotes_backslash():
     """Sum\\mary."""
 
 
+@expect('D301: Use r""" if any backslashes in a docstring')
+def double_quotes_backslash_uppercase():
+    R"""Sum\\mary."""
+
+
 if sys.version_info[0] <= 2:
     @expect('D302: Use u""" for Unicode docstrings')
-    def lasewnlkjl():
+    def unicode_unmarked():
         """Юникод."""